Saul Winderbaum - Academia.edu (original) (raw)

Papers by Saul Winderbaum

Solar Energy Materials and Solar Cells, 1997

Reactive ion etching (RIE) has been applied and developed as a method for texturing polycrystaUin... more Reactive ion etching (RIE) has been applied and developed as a method for texturing polycrystaUine silicon solar cells. Two structures (microgrooves and pyramids) were produced in this work. Reflectivity measurements between 400-1200 nm show an overall reflectance of 5.6% for pyramid and 7.9 % for groove structures, These results are better than those using wet anisotropic etch techniques on single-crystal silicon. RIE texturing was performed on cast polycrystalline silicon and produced better reflection control than standard TiO 2 antireflection coatings. RIE texturing also changes the incidence angle of light into the silicon, this improves the response for long wavelengths which can be utilised in thin film, polycrystalline or amorphous silicon solar cells.

The PSG layer growth and removal is a critical process step in the crystalline silicon solar cell... more The PSG layer growth and removal is a critical process step in the crystalline silicon solar cell production process. Due to the physical setup of in line doper and diffusion systems, high levels of uniformity can be achieved reaching standard deviation on and below the order of 1 Ohm/square for a 65 Ohm emitter. However using an in line doper limits the minimum amount of liquid dopant source in order to achieve the uniformity requirements of a high efficiency solar cell and that in turn raises the surface dopant concentration and the Phosphorous concentration in the PSG layer itself making it more difficult to remove completely. This will have a direct impact on the blue wavelength response and cell efficiency. In general SIMS measurement are traditionally used for measuring surface and depth dopant profiles, however this method is not ready available in most production facilities, hence we develop a simple and practical method to optimize this PSG layer using ellipsometry for process optimization.

Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 1997

Reflection losses in passivated emitter solar cell polycrystalline silicon solar cells have been ... more Reflection losses in passivated emitter solar cell polycrystalline silicon solar cells have been reduced by the application of a double layer antireflection coating of plasma enhanced chemical vapor deposition silicon nitride ͑PECVD Si x N y H z ͒. The layer was deposited in a single wafer parallel plate reactor powered by a 13.56 MHz rf power supply using SiH 4 and NH 3 as the reactive gases. The layers deposited had refractive indexes of 2.50 and 1.95 at HeNe wavelength and thicknesses of 42.5 and 64.5 nanometers ͑nm͒, respectively. The overall reflectance measured in the wavelength range between 350 and 1150 nm was 8.5%. The extinction coefficient of the high refractive index film showed a significant increase in absorption for short wavelengths. However, the improvement in current collection was higher than expected from the overall reflectance and absorption of the film. Short circuit current was increased by 49% and open circuit voltage increased by 3.3% when compared with uncoated cells. These results imply a passivation effect which increases the open circuit voltage beyond the value expected solely from the current collection addition.

... Saul Winderbaum', Anthony J. Leo', Stephen P. Shea, Timothy D.. Kova13, Bikash Kuma... more ... Saul Winderbaum', Anthony J. Leo', Stephen P. Shea, Timothy D.. Kova13, Bikash Kumar4 1. Shamash Australia Pty Ltd, 2. bp solar Australia, 3. bp solar USA, 4 ... VOC (mV) JsC*Voc % gain DOE 1-1 599.0 7.6 DOEl 2 595.7 6.9 DOE 1-3 597.7 6.0 DOEl 4 596.9 6.9 DOE 1-5 598.0 ...

Deposition of silicon nitride layers on top of silicon wafers using industrial plasma enhanced ch... more Deposition of silicon nitride layers on top of silicon wafers using industrial plasma enhanced chemical vapor deposition systems is a major component in today's manufacturing of silicon solar cells. Previous work has demonstrated non-uniformity in the optical properties within the bulk of dynamically deposited layers using such in-line systems. A gradient in the optical properties within the layer emphasizes the need for optical characterization as a function of the layer's depth. This paper presents an advanced method to characterize dynamically deposited silicon nitride layers, where the modelling of the experimental ellipsometry spectra is performed by grading of the Tauc-Lorentz optical parameters along the normal of the layer. Significant improvements are demonstrated over the standard, more commonly used Tauc-Lorentz modelling procedure; mainly by revealing of the depth profiles of the layer's optical properties.

Applied Physics Letters, 2016

Dynamic deposition of silicon nitrides using in-line plasma enhanced chemical vapor deposition sy... more Dynamic deposition of silicon nitrides using in-line plasma enhanced chemical vapor deposition systems results in non-uniform structure of the dielectric layer. Appropriate analysis of such layers requires the optical characterization to be performed as a function of the layer's depth. This work presents a method to characterize dynamically deposited silicon nitride layers. The method is based on the fitting of experimental spectroscopic ellipsometry data via grading of Tauc-Lorentz optical parameters through the depth of the layer. When compared with the standard Tauc-Lorentz fitting procedure, used in previous studies, the improved method is demonstrating better quality fits to the experimental data and revealing more accurate optical properties of the dielectric layers. The most significant advantage of the method is the ability to extract the depth profile of the optical properties along the direction of the layer normal. This is enabling a better understanding of layers deposited using dynamic plasma enhanced chemical vapor deposition systems frequently used in the photovoltaic industry.

Solar Energy, 2019

Plasma-enhanced chemical-vapor deposition systems are commonly used to deposit aluminum oxide (Al... more Plasma-enhanced chemical-vapor deposition systems are commonly used to deposit aluminum oxide (AlO x) on silicon wafers in the production of silicon solar cells. This study investigates the impact of the deposition conditions on the obtained surface passivation quality of p-type wafers. It is the first to investigate the impact of all the five main process parameters. The ratio between the microwave power and the total gas flow rate is identified as a critical condition to form thermally stable layers. We find that the most significant parameter for high quality surface passivation is the flow rate ratio of nitrous oxide (N 2 O) to tri-methyl-aluminum (TMA). Higher flow rate ratio ([N 2 O]/[TMA]) is required to achieve better passivation for fired wafers, whereas lower ratio is preferred when the firing process is not permissible. Elastic-recoil detection analysis reveals that the gas flow rate ratio has a significant impact on the likely direction of hydrogen released from the layer during firing (either to the interface with the silicon wafer or to the environment). Surprisingly, the atomic concentration of aluminum and oxygen is found to be almost stoichiometric regardless of the wide range of the gas flow rate ratios studied in this paper. We investigated the impact of the five most critical PECVD process

IEEE Journal of Photovoltaics, 2017

Amorphous silicon nitride has become the state-ofthe-art antireflection coating for silicon solar... more Amorphous silicon nitride has become the state-ofthe-art antireflection coating for silicon solar cells. Optimization of silicon nitride films requires consideration of both the film's optical and electrical properties. It is commonly assumed that silicon-rich silicon nitride films (films with high refractive index) provide better surface passivation, compared to that obtained by films with lower indices. However, silicon-rich films are usually very absorptive in the short (and even medium) wavelength range. Development of low absorption silicon nitride films, that provide good surface passivation, is therefore highly valuable. In this study we compare nine different industrial silicon nitride films, all with similarly low refractive index of 2.09 ± 0.01 measured at 633 nm. We demonstrate that these films exhibit very different electrical, chemical, and optical properties despite their similar refractive index values and correlate these differences with the specific deposition conditions. As a result of this investigation, we have developed industrial thermally stable low-absorbing silicon nitride films that provide excellent surface passivation, with surface saturation current density of 7 fA/cm 2 on both n-and p-type wafers. We demonstrate that the developed low absorption films provide surface passivation with equal quality to that obtained by industrial silicon-rich silicon nitride films.

Surface and Coatings Technology, 2017

Plasma enhanced chemical vapor deposition (PECVD) is ubiquitously used in the crystalline silicon... more Plasma enhanced chemical vapor deposition (PECVD) is ubiquitously used in the crystalline silicon photovoltaics industry to deposit surface passivation and anti-reflection coatings. Aluminum oxide deposited by PECVD is becoming an increasingly common rear surface passivation layer, due to the growing market share of solar cells with partial rear contacts, such as the passivated emitter and rear solar cell. In this study, we use in-situ monitoring to investigate the correlation between the PECVD plasma properties and the resulting aluminum oxide film properties. Although no linear correlation between the density of the constituent radicals (aluminum, oxygen, and hydrogen) in the plasma and the surface passivation quality was observed, we did identify optimum processing conditions for a high quality surface passivation layer using in-situ plasma monitoring. This study also highlights the limited knowledge that currently exists within the photovoltaic community regarding plasma characterization and its impact on device performance.

2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC), 2016

Aluminum oxide has been highlighted as a promising surface passivation layer for p-type silicon s... more Aluminum oxide has been highlighted as a promising surface passivation layer for p-type silicon surface. To-date, most of the studies have focused on aluminum oxide layers deposited with atomic layer deposition systems which have lower throughput than industrial plasma-based systems. In this study, the effects of deposition conditions on the electrical and optical properties of aluminum oxide deposited by an industrial plasma enhanced chemical vapor deposition system are presented. Low saturation current density of 1.9 fA/cm2 was achieved by as deposited layer on p-type Czochralski wafer. The most significant deposition process factor for high quality surface passivation was found to be the gas flow rate ratio between nitrous oxide and tri-methyl-aluminum.

Conference Record of the Twenty-Eighth IEEE Photovoltaic Specialists Conference - 2000 (Cat. No.00CH37036)

The possible benefits of phosphorus gettering as applied to production multicrystalline silicon w... more The possible benefits of phosphorus gettering as applied to production multicrystalline silicon wafers have been evaluated. After optimization of an open tube POCl 3 process, relatively low temperatures and short times have been found to significantly improve the minority carrier lifetime of most wafers. The possible gettering action stemming from the industrial process of phosphorus diffusion has also been investigated and found to be similarly effective. Average lifetimes of 45µs (diffusion length of 360µm) were obtained, with some wafers reaching maximum values up to 130µs. Lifetime monitoring of a commercial cell fabrication line has also enabled characterization of the voltage limits imposed by the standard emitter and aluminum back-surface-field. The results indicate that the bulk, as improved by emitter gettering, is generally not the limiting factor on cell performance.

2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC), 2016

The refractive index at 633 nm is often used to characterize silicon nitride films. Besides provi... more The refractive index at 633 nm is often used to characterize silicon nitride films. Besides providing information about the reflection at this particular wavelength, it is frequently used to indicate additional information regarding the film's absorption and even regarding its surface passivation quality. In this study, we compare nine different silicon nitride films, all with a similar refractive index at 633 nm (2.09±0.01). We demonstrate that these films exhibit very different electrical, chemical and optical properties despite their similar refractive index values. As a result of this investigation, we have developed industrial low-absorption silicon nitride films that provide excellent surface passivation, with saturation current density of 7 fA/cm2 on both n- and p-type wafers. This surface passivation quality is equal to that obtained by industrial silicon-rich silicon nitride films. All the films developed in this study were fabricated using industrial equipment and are thermally stable.

As industrially produced solar cells become thinner and more efficient, silicon nitride (SiN) fil... more As industrially produced solar cells become thinner and more efficient, silicon nitride (SiN) films are becoming increasingly important. At present, the favored means of producing these films is by remote plasma-enhanced chemical vapour deposition (RPECVD). In this paper, using films produced by an industrial Roth & Rau SiNA RPECVD reactor, we investigate the surface passivation qualities of SiN films on phosphorus emitters. In industry, these SiN films are regularly subjected to anneals during metalisation. As such, we have endavoured to understand the effect that annealling has on the SiN films and seek to determine the most appropriate annealling conditions to optimise the surface passivation qualities of SiN on phosphorus emitters. Inital annealing results have shown an average 64 % increase in surface passivation across the range of refractive indices tested. In addition, a decrease in the standard deviation of the results indicates that annealing increases the uniformity of th...

As industrially produced solar cells become thinner and more efficient, silicon nitride (SiN) fil... more As industrially produced solar cells become thinner and more efficient, silicon nitride (SiN) films are becoming increasingly important. At present, the favored means of producing these films is by remote plasma-enhanced chemical vapour deposition (RPECVD). In this paper, using films produced by an industrial Roth & Rau SiNA RPECVD reactor, we investigate the surface passivation qualities of SiN films on phosphorus emitters. In industry, these SiN films are regularly subjected to anneals during metalisation. As such, we have endavoured to understand the effect that annealling has on the SiN films and seek to determine the most appropriate annealling conditions to optimise the surface passivation qualities of SiN on phosphorus emitters. Inital annealing results have shown an average 64% increase in surface passivation across the range of refractive indices tested. In addition, a decrease in the standard deviation of the results indicates that annealing increases the uniformity of the...

Reactive ion etching (RIE) of lithium niobate substrates has been performed using CF 4 :0 2 chemi... more Reactive ion etching (RIE) of lithium niobate substrates has been performed using CF 4 :0 2 chemistry. A maximum etch rate of 38 A/rmin was obtained, and a deepest etch of 1.2 ýtm was achieved. The x-cut crystal orientation of the lithium niobate crystal etched more slowly than the z-cut orientation, at a ratio of 8:15. Sidewall roughness was minimised at the expense of etch rate by increasing the oxygen flow rate for fixed CF 4 flow rate. The achieved etch rate is suitable for low refractive index contrast devices such as integrated optical gratings or lenses. However the low etch rate is impractical for low drive voltage etched modulators.

... Saul Winderbaum', Anthony J. Leo', Stephen P. Shea, Timothy D.. Kova13, Bikash Kuma... more ... Saul Winderbaum', Anthony J. Leo', Stephen P. Shea, Timothy D.. Kova13, Bikash Kumar4 1. Shamash Australia Pty Ltd, 2. bp solar Australia, 3. bp solar USA, 4 ... VOC (mV) JsC*Voc % gain DOE 1-1 599.0 7.6 DOEl 2 595.7 6.9 DOE 1-3 597.7 6.0 DOEl 4 596.9 6.9 DOE 1-5 598.0 ...

As industry moves towards thinner and more efficient solar cell designs, the role of silicon nitr... more As industry moves towards thinner and more efficient solar cell designs, the role of silicon nitride films (SiN) is becoming more important. Besides near ideal anti-reflection properties, these films can also offer superior surface and bulk passivation qualities. In this paper, surface passivation properties of n+ emitters by industrial remote plasma-enhanced chemical vapour deposited (RPECVD) amorphous SiN films are investigated. In addition, the hydrogenation capabilities of SiN films will be measured with respect to the bulk passivation of multi-crystalline silicon.

An anomalous behaviour, which we term 'second lifetime recovery effect', was observed when studyi... more An anomalous behaviour, which we term 'second lifetime recovery effect', was observed when studying the thermal behaviour of the surface passivation of silicon nitride (SiN) deposited by Plasma Enhanced Chemical Deposition (PECVD) on p-type silicon wafers. The behaviour can be characterized by two local maxima in the effective lifetime vs. anneal duration curve. The existence of a second local maximum suggests a previously unexplained behaviour in PECVD SiN films. Several possible mechanisms that could explain the effect are explored in this work. Initial characterization of the thermal behaviour suggests that the mechanism is thermally activated, with an initial time delay in the activation, and is a transient process once activated.

Solar Energy Materials and Solar Cells, 1997

Reactive ion etching (RIE) has been applied and developed as a method for texturing polycrystaUin... more Reactive ion etching (RIE) has been applied and developed as a method for texturing polycrystaUine silicon solar cells. Two structures (microgrooves and pyramids) were produced in this work. Reflectivity measurements between 400-1200 nm show an overall reflectance of 5.6% for pyramid and 7.9 % for groove structures, These results are better than those using wet anisotropic etch techniques on single-crystal silicon. RIE texturing was performed on cast polycrystalline silicon and produced better reflection control than standard TiO 2 antireflection coatings. RIE texturing also changes the incidence angle of light into the silicon, this improves the response for long wavelengths which can be utilised in thin film, polycrystalline or amorphous silicon solar cells.

The PSG layer growth and removal is a critical process step in the crystalline silicon solar cell... more The PSG layer growth and removal is a critical process step in the crystalline silicon solar cell production process. Due to the physical setup of in line doper and diffusion systems, high levels of uniformity can be achieved reaching standard deviation on and below the order of 1 Ohm/square for a 65 Ohm emitter. However using an in line doper limits the minimum amount of liquid dopant source in order to achieve the uniformity requirements of a high efficiency solar cell and that in turn raises the surface dopant concentration and the Phosphorous concentration in the PSG layer itself making it more difficult to remove completely. This will have a direct impact on the blue wavelength response and cell efficiency. In general SIMS measurement are traditionally used for measuring surface and depth dopant profiles, however this method is not ready available in most production facilities, hence we develop a simple and practical method to optimize this PSG layer using ellipsometry for process optimization.

Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 1997

Reflection losses in passivated emitter solar cell polycrystalline silicon solar cells have been ... more Reflection losses in passivated emitter solar cell polycrystalline silicon solar cells have been reduced by the application of a double layer antireflection coating of plasma enhanced chemical vapor deposition silicon nitride ͑PECVD Si x N y H z ͒. The layer was deposited in a single wafer parallel plate reactor powered by a 13.56 MHz rf power supply using SiH 4 and NH 3 as the reactive gases. The layers deposited had refractive indexes of 2.50 and 1.95 at HeNe wavelength and thicknesses of 42.5 and 64.5 nanometers ͑nm͒, respectively. The overall reflectance measured in the wavelength range between 350 and 1150 nm was 8.5%. The extinction coefficient of the high refractive index film showed a significant increase in absorption for short wavelengths. However, the improvement in current collection was higher than expected from the overall reflectance and absorption of the film. Short circuit current was increased by 49% and open circuit voltage increased by 3.3% when compared with uncoated cells. These results imply a passivation effect which increases the open circuit voltage beyond the value expected solely from the current collection addition.

... Saul Winderbaum', Anthony J. Leo', Stephen P. Shea, Timothy D.. Kova13, Bikash Kuma... more ... Saul Winderbaum', Anthony J. Leo', Stephen P. Shea, Timothy D.. Kova13, Bikash Kumar4 1. Shamash Australia Pty Ltd, 2. bp solar Australia, 3. bp solar USA, 4 ... VOC (mV) JsC*Voc % gain DOE 1-1 599.0 7.6 DOEl 2 595.7 6.9 DOE 1-3 597.7 6.0 DOEl 4 596.9 6.9 DOE 1-5 598.0 ...

Deposition of silicon nitride layers on top of silicon wafers using industrial plasma enhanced ch... more Deposition of silicon nitride layers on top of silicon wafers using industrial plasma enhanced chemical vapor deposition systems is a major component in today's manufacturing of silicon solar cells. Previous work has demonstrated non-uniformity in the optical properties within the bulk of dynamically deposited layers using such in-line systems. A gradient in the optical properties within the layer emphasizes the need for optical characterization as a function of the layer's depth. This paper presents an advanced method to characterize dynamically deposited silicon nitride layers, where the modelling of the experimental ellipsometry spectra is performed by grading of the Tauc-Lorentz optical parameters along the normal of the layer. Significant improvements are demonstrated over the standard, more commonly used Tauc-Lorentz modelling procedure; mainly by revealing of the depth profiles of the layer's optical properties.

Applied Physics Letters, 2016

Dynamic deposition of silicon nitrides using in-line plasma enhanced chemical vapor deposition sy... more Dynamic deposition of silicon nitrides using in-line plasma enhanced chemical vapor deposition systems results in non-uniform structure of the dielectric layer. Appropriate analysis of such layers requires the optical characterization to be performed as a function of the layer's depth. This work presents a method to characterize dynamically deposited silicon nitride layers. The method is based on the fitting of experimental spectroscopic ellipsometry data via grading of Tauc-Lorentz optical parameters through the depth of the layer. When compared with the standard Tauc-Lorentz fitting procedure, used in previous studies, the improved method is demonstrating better quality fits to the experimental data and revealing more accurate optical properties of the dielectric layers. The most significant advantage of the method is the ability to extract the depth profile of the optical properties along the direction of the layer normal. This is enabling a better understanding of layers deposited using dynamic plasma enhanced chemical vapor deposition systems frequently used in the photovoltaic industry.

Solar Energy, 2019

Plasma-enhanced chemical-vapor deposition systems are commonly used to deposit aluminum oxide (Al... more Plasma-enhanced chemical-vapor deposition systems are commonly used to deposit aluminum oxide (AlO x) on silicon wafers in the production of silicon solar cells. This study investigates the impact of the deposition conditions on the obtained surface passivation quality of p-type wafers. It is the first to investigate the impact of all the five main process parameters. The ratio between the microwave power and the total gas flow rate is identified as a critical condition to form thermally stable layers. We find that the most significant parameter for high quality surface passivation is the flow rate ratio of nitrous oxide (N 2 O) to tri-methyl-aluminum (TMA). Higher flow rate ratio ([N 2 O]/[TMA]) is required to achieve better passivation for fired wafers, whereas lower ratio is preferred when the firing process is not permissible. Elastic-recoil detection analysis reveals that the gas flow rate ratio has a significant impact on the likely direction of hydrogen released from the layer during firing (either to the interface with the silicon wafer or to the environment). Surprisingly, the atomic concentration of aluminum and oxygen is found to be almost stoichiometric regardless of the wide range of the gas flow rate ratios studied in this paper. We investigated the impact of the five most critical PECVD process

IEEE Journal of Photovoltaics, 2017

Amorphous silicon nitride has become the state-ofthe-art antireflection coating for silicon solar... more Amorphous silicon nitride has become the state-ofthe-art antireflection coating for silicon solar cells. Optimization of silicon nitride films requires consideration of both the film's optical and electrical properties. It is commonly assumed that silicon-rich silicon nitride films (films with high refractive index) provide better surface passivation, compared to that obtained by films with lower indices. However, silicon-rich films are usually very absorptive in the short (and even medium) wavelength range. Development of low absorption silicon nitride films, that provide good surface passivation, is therefore highly valuable. In this study we compare nine different industrial silicon nitride films, all with similarly low refractive index of 2.09 ± 0.01 measured at 633 nm. We demonstrate that these films exhibit very different electrical, chemical, and optical properties despite their similar refractive index values and correlate these differences with the specific deposition conditions. As a result of this investigation, we have developed industrial thermally stable low-absorbing silicon nitride films that provide excellent surface passivation, with surface saturation current density of 7 fA/cm 2 on both n-and p-type wafers. We demonstrate that the developed low absorption films provide surface passivation with equal quality to that obtained by industrial silicon-rich silicon nitride films.

Surface and Coatings Technology, 2017

Plasma enhanced chemical vapor deposition (PECVD) is ubiquitously used in the crystalline silicon... more Plasma enhanced chemical vapor deposition (PECVD) is ubiquitously used in the crystalline silicon photovoltaics industry to deposit surface passivation and anti-reflection coatings. Aluminum oxide deposited by PECVD is becoming an increasingly common rear surface passivation layer, due to the growing market share of solar cells with partial rear contacts, such as the passivated emitter and rear solar cell. In this study, we use in-situ monitoring to investigate the correlation between the PECVD plasma properties and the resulting aluminum oxide film properties. Although no linear correlation between the density of the constituent radicals (aluminum, oxygen, and hydrogen) in the plasma and the surface passivation quality was observed, we did identify optimum processing conditions for a high quality surface passivation layer using in-situ plasma monitoring. This study also highlights the limited knowledge that currently exists within the photovoltaic community regarding plasma characterization and its impact on device performance.

2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC), 2016

Aluminum oxide has been highlighted as a promising surface passivation layer for p-type silicon s... more Aluminum oxide has been highlighted as a promising surface passivation layer for p-type silicon surface. To-date, most of the studies have focused on aluminum oxide layers deposited with atomic layer deposition systems which have lower throughput than industrial plasma-based systems. In this study, the effects of deposition conditions on the electrical and optical properties of aluminum oxide deposited by an industrial plasma enhanced chemical vapor deposition system are presented. Low saturation current density of 1.9 fA/cm2 was achieved by as deposited layer on p-type Czochralski wafer. The most significant deposition process factor for high quality surface passivation was found to be the gas flow rate ratio between nitrous oxide and tri-methyl-aluminum.

Conference Record of the Twenty-Eighth IEEE Photovoltaic Specialists Conference - 2000 (Cat. No.00CH37036)

The possible benefits of phosphorus gettering as applied to production multicrystalline silicon w... more The possible benefits of phosphorus gettering as applied to production multicrystalline silicon wafers have been evaluated. After optimization of an open tube POCl 3 process, relatively low temperatures and short times have been found to significantly improve the minority carrier lifetime of most wafers. The possible gettering action stemming from the industrial process of phosphorus diffusion has also been investigated and found to be similarly effective. Average lifetimes of 45µs (diffusion length of 360µm) were obtained, with some wafers reaching maximum values up to 130µs. Lifetime monitoring of a commercial cell fabrication line has also enabled characterization of the voltage limits imposed by the standard emitter and aluminum back-surface-field. The results indicate that the bulk, as improved by emitter gettering, is generally not the limiting factor on cell performance.

2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC), 2016

The refractive index at 633 nm is often used to characterize silicon nitride films. Besides provi... more The refractive index at 633 nm is often used to characterize silicon nitride films. Besides providing information about the reflection at this particular wavelength, it is frequently used to indicate additional information regarding the film's absorption and even regarding its surface passivation quality. In this study, we compare nine different silicon nitride films, all with a similar refractive index at 633 nm (2.09±0.01). We demonstrate that these films exhibit very different electrical, chemical and optical properties despite their similar refractive index values. As a result of this investigation, we have developed industrial low-absorption silicon nitride films that provide excellent surface passivation, with saturation current density of 7 fA/cm2 on both n- and p-type wafers. This surface passivation quality is equal to that obtained by industrial silicon-rich silicon nitride films. All the films developed in this study were fabricated using industrial equipment and are thermally stable.

As industrially produced solar cells become thinner and more efficient, silicon nitride (SiN) fil... more As industrially produced solar cells become thinner and more efficient, silicon nitride (SiN) films are becoming increasingly important. At present, the favored means of producing these films is by remote plasma-enhanced chemical vapour deposition (RPECVD). In this paper, using films produced by an industrial Roth & Rau SiNA RPECVD reactor, we investigate the surface passivation qualities of SiN films on phosphorus emitters. In industry, these SiN films are regularly subjected to anneals during metalisation. As such, we have endavoured to understand the effect that annealling has on the SiN films and seek to determine the most appropriate annealling conditions to optimise the surface passivation qualities of SiN on phosphorus emitters. Inital annealing results have shown an average 64 % increase in surface passivation across the range of refractive indices tested. In addition, a decrease in the standard deviation of the results indicates that annealing increases the uniformity of th...

As industrially produced solar cells become thinner and more efficient, silicon nitride (SiN) fil... more As industrially produced solar cells become thinner and more efficient, silicon nitride (SiN) films are becoming increasingly important. At present, the favored means of producing these films is by remote plasma-enhanced chemical vapour deposition (RPECVD). In this paper, using films produced by an industrial Roth & Rau SiNA RPECVD reactor, we investigate the surface passivation qualities of SiN films on phosphorus emitters. In industry, these SiN films are regularly subjected to anneals during metalisation. As such, we have endavoured to understand the effect that annealling has on the SiN films and seek to determine the most appropriate annealling conditions to optimise the surface passivation qualities of SiN on phosphorus emitters. Inital annealing results have shown an average 64% increase in surface passivation across the range of refractive indices tested. In addition, a decrease in the standard deviation of the results indicates that annealing increases the uniformity of the...

Reactive ion etching (RIE) of lithium niobate substrates has been performed using CF 4 :0 2 chemi... more Reactive ion etching (RIE) of lithium niobate substrates has been performed using CF 4 :0 2 chemistry. A maximum etch rate of 38 A/rmin was obtained, and a deepest etch of 1.2 ýtm was achieved. The x-cut crystal orientation of the lithium niobate crystal etched more slowly than the z-cut orientation, at a ratio of 8:15. Sidewall roughness was minimised at the expense of etch rate by increasing the oxygen flow rate for fixed CF 4 flow rate. The achieved etch rate is suitable for low refractive index contrast devices such as integrated optical gratings or lenses. However the low etch rate is impractical for low drive voltage etched modulators.

... Saul Winderbaum', Anthony J. Leo', Stephen P. Shea, Timothy D.. Kova13, Bikash Kuma... more ... Saul Winderbaum', Anthony J. Leo', Stephen P. Shea, Timothy D.. Kova13, Bikash Kumar4 1. Shamash Australia Pty Ltd, 2. bp solar Australia, 3. bp solar USA, 4 ... VOC (mV) JsC*Voc % gain DOE 1-1 599.0 7.6 DOEl 2 595.7 6.9 DOE 1-3 597.7 6.0 DOEl 4 596.9 6.9 DOE 1-5 598.0 ...

As industry moves towards thinner and more efficient solar cell designs, the role of silicon nitr... more As industry moves towards thinner and more efficient solar cell designs, the role of silicon nitride films (SiN) is becoming more important. Besides near ideal anti-reflection properties, these films can also offer superior surface and bulk passivation qualities. In this paper, surface passivation properties of n+ emitters by industrial remote plasma-enhanced chemical vapour deposited (RPECVD) amorphous SiN films are investigated. In addition, the hydrogenation capabilities of SiN films will be measured with respect to the bulk passivation of multi-crystalline silicon.

An anomalous behaviour, which we term 'second lifetime recovery effect', was observed when studyi... more An anomalous behaviour, which we term 'second lifetime recovery effect', was observed when studying the thermal behaviour of the surface passivation of silicon nitride (SiN) deposited by Plasma Enhanced Chemical Deposition (PECVD) on p-type silicon wafers. The behaviour can be characterized by two local maxima in the effective lifetime vs. anneal duration curve. The existence of a second local maximum suggests a previously unexplained behaviour in PECVD SiN films. Several possible mechanisms that could explain the effect are explored in this work. Initial characterization of the thermal behaviour suggests that the mechanism is thermally activated, with an initial time delay in the activation, and is a transient process once activated.