Frédéric Cayrel - Academia.edu (original) (raw)

Papers by Frédéric Cayrel

Solid State Phenomena, 2004

Solid State Phenomena, 2005

Solid State Phenomena, 2008

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2012

Gallium nitride (GaN) is a promising material for power electronic devices. Due to GaN sensitivit... more Gallium nitride (GaN) is a promising material for power electronic devices. Due to GaN sensitivity to high temperature treatments, dopant activation, after ion implant, is one of the major critical steps to be overcome. An annealing cap layer is then mandatory during high temperature treatment to avoid degradations. In this work, cap layers, such as AlN and SiOx, were deposited

Nanoscale Research Letters, 2014

A perfect control of nanostructure growth is a prerequisite for the development of electronic and... more A perfect control of nanostructure growth is a prerequisite for the development of electronic and optoelectronic device/systems. In this article, we demonstrate the growth of various ZnO-derived nanostructures, including well-ordered arrays of high aspect ratio single crystalline nanowires with preferred growth direction along the [0001] axis, nanowalls, and hybrid nanowire-nanowall structures. The growths of the various ZnO nanostructures have been carried out on SiC substrates in a horizontal furnace, using Au thin film as catalyst. From experimental observations, we have ascribed the growth mechanisms of the different ZnO nanostructures to be a combination of catalytic-assisted and non-catalytic-assisted vapor-liquid-solid (VLS) processes. We have also found that the different ZnO nanoarchitectures' material evolution is governed by a Zn cluster drift effects on the SiC surface mainly driven by growth temperature. Au thin film thickness, growth time, and temperature are the parameters to optimize in order to obtain the different ZnO nanoarchitectures.

Materials Science Forum, 2009

... [2] T. Palacios, A. Chakraborty, S. Heikman, S. Keller, SP DenBaars, UK Mishra: IEEE Electron... more ... [2] T. Palacios, A. Chakraborty, S. Heikman, S. Keller, SP DenBaars, UK Mishra: IEEE Electron Device Letters Vol. 27 (2006), p. 13 [3] CP Chan, J. Gao, TM Yue, C. Ng. Surya, AB Djuric, PC-K. Liu, M. Li: IEEE Transactions on Electron Devices Vol. 53 (2006), p. 2266 ...

3C-SiC, the only polytype which can be heteroepitaxially grown on large diameter silicon substrat... more 3C-SiC, the only polytype which can be heteroepitaxially grown on large diameter silicon substrates, is a promising material to achieve power Schottky diodes. To carry out such diodes, high quality ohmic contacts are required. In this work, ohmic contacts were investigated on in situ highly n-doped 3C-SiC epilayers grown on (100) cheap silicon substrates. Different metals such as nickel, titanium, aluminum and gold were used to carry out the contacts. Classical circular Transfert Length Method (c-TLM) structures were prepared to evaluate the specific contact resistance. Ni and Ti-Ni contacts were annealed between 950°C and 1050°C while Al and Ti-Au contacts were annealed between 300°C and 600°C. The specific contact resistance was then determined by using c-TLM patterns. For each investigated contact, the best specific contact resistance values obtained are lower than 2x10 -5 Ω.cm 2 , even consecutively to a low temperature annealing.

physica status solidi (c), 2010

Materials Science Forum, 2010

During device manufacture, metal contamination has a large effect on silicon-based device perform... more During device manufacture, metal contamination has a large effect on silicon-based device performance. Of the available gettering techniques, helium implantation is widely used but the high fluence required is a major drawback. In this paper, the impact of F coimplantation on He implantation-induced defects has been carefully studied. Firstly, our results show that both interstitial and vacancy defects are present in the defect band for all implantation conditions. We show that F implantation may lead to cavity formation at high temperature as expected. The TEM observations also show that, at high temperature, the shape and size of the He-induced defects are significantly affected by the fluorine co-implantation. In particular, cavities are drastically modified by the addition of F, which promotes cavity growth. These results enable us to understand the defect interactions better and constitute a good background to gettering techniques for future device processing.

Solid State Phenomena, 2004

Solid State Phenomena, 2002

Metal contaminants, even at low concentration, are able to degrade the performance of silicon-bas... more Metal contaminants, even at low concentration, are able to degrade the performance of silicon-based devices. It has been shown that high dose helium implants in silicon, with a subsequent thermal anneal, produce cavities and dislocations, which are able to getter these impurities . However, most of the papers in the literature focus on the interaction between these cavities and the metal contaminants (Fe, Cu and Au) [1-4], they omit their interactions with dopants, which can be found in any devices with high concentrations compared with contamination level. The relation cavity layer-dopants can largely influence the structure through diffusion or segregation phenomena as well as the electrical activity of the components [4-5] and can become a drawback of this gettering technique. In this paper we will focus on the strong interaction between this layer and dopants (Boron and Phosphorus) in terms of dopant segregation. In this work, P and N-type <111> Si wafers, uniformly doped respectively with B and P with concentrations of about 3×10 18 cm -3 , were used. In this way, the initial dopant concentration was kept below the solid solubility. The helium implantation was performed using always the same conditions (40 keV and 5 ×10 16 cm -2 ) at room temperature. Furnace Annealing (FA) and Rapid Thermal Annealing (RTA), for various times ranging from 10s to 1h and temperatures in the range of 650°C up to 1000°C, were applied on the samples. Secondary Ion Mass Spectrometry (SIMS) was used to follow the dopant profile in the vicinity of the cavities as well as in the bulk, using conditions that prevented from such measurement artifacts. Spreading Resistance Profilometry (SRP) measurements, which allows us to determine the carrier concentration profiles, are presented. For better understanding, we used TEM measurements from previous work . We will enlighten, in this paper, the strong interaction between the cavity layer, induced by helium implantation, and both boron and phosphorus. After evidencing the impact of He gettering step on the dopant profile and in order to study the dopant-cavity layer interaction, we use uniformly N and P doped wafers implanted with helium at high dose and annealed using RTA and FA system. To avoid any precipitation phenomena, conditions were chosen not to exceed the dopant solid solubility value. Our experimental results exhibit a large trapping of both species within the cavity layer (see and 2) that occurs since the early stage of the annealing. SRP measurements clearly indicate the importance of the He post-implantation anneal to obtain a complete activation of the dopant (See . These results enable us to have better understanding of the effect of the He gettering step as well as its interaction with dopant atoms. Moreover, we will compare and discuss the impact of this stage on P and B doped layers. This is of great interest for present and future device fabrication.

MRS Proceedings, 2008

ABSTRACT The fabrication of highly doped and ultra-shallow junctions in silicon is a very challen... more ABSTRACT The fabrication of highly doped and ultra-shallow junctions in silicon is a very challenging problem for the materials scientist. The activation levels which are targeted are well beyond the solubility limit of current dopants in Si and, ideally, they should not diffuse during the activation annealing. In practice, the situation is even worse and when boron is implanted into silicon excess Si interstitial atoms are generated which enhance boron diffusion and favor the formation of Boron-Silicon Interstitials Clusters (BICs). An elegant approach to overcome these difficulties is to enrich the Si layers where boron will be implanted with vacancies before or during the activation annealing. Spectacular results have been recently brought to the community showing both a significant control over dopant diffusion and an increased activation of boron in such layers. In general, the enrichment of the Si layers with vacancies is obtained by Si+ implantation at high energy. We have recently developed an alternative approach in which the vacancies are injected from populations of empty voids undergoing Ostwald ripening during annealing. While different, the effects are also spectacular. The goal of this work is to establish a fair evaluation of these different approaches under technologically relevant conditions. The application domains of both techniques are discussed and future directions for their development/improvement are indicated.

Materials Science Forum, 2011

Materials Science Forum, 2012

In this paper, we studied the influence of nitrogen implantation dose on both physical and electr... more In this paper, we studied the influence of nitrogen implantation dose on both physical and electrical properties in 3C-SiC grown on Si (100) substrate. Scanning Transmission Electron Microscopy characterizations prove that high dose is responsible for amorphization of the implanted layer and the high defect density after annealing. A high V-shape defect density is still found in the implanted layer after an annealing at 1350°C. By lowering the dose, the layer is less damaged and no amorphization is observed. For the different doses, low Specific Contact Resistances are measured using Ti/Ni contacts. The Specific Contact Resistance value decreases from 8x10 -6 Ω.cm 2 for the high dose to 3.2x10 -6 Ω.cm 2 with decreasing the dose. Furthermore, the dopant activation ratio, evaluated by quantitative SSRM measurements, is improved at the same time from 17% (for the high dose) to 60% (for the low dose). This work demonstrates that high activation ratio can be achieved consecutively to a nitrogen implantation at reasonable implantation fluence.

Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2006

Dielectric function of disorder in single-crystalline silicon (c-Si) implanted by He with energy ... more Dielectric function of disorder in single-crystalline silicon (c-Si) implanted by He with energy of 40keV and fluences from 1×1016 to 1×1017cm−2 were determined around the E1 and E2 critical points (CPs) by spectroscopic ellipsometry. The implanted material was modeled by an effective medium composition of c-Si and damaged Si. The dielectric function of damaged Si was calculated using the model

physica status solidi (c), 2010

... IEEE Internat. 16.1.1 16.1.3 (2003). [5] T. Palacios, A. Chakraborty, S. Heikman, S. Keller, ... more ... IEEE Internat. 16.1.1 16.1.3 (2003). [5] T. Palacios, A. Chakraborty, S. Heikman, S. Keller, SP DenBaars, and UK Mishra. Electron Device Lett., IEEE 27(1), 13-15 (2006). [6] CP Chan, J. Gao, TM Yue, C.Ng. Surya, AB Djuric, PC-K. Liu, and M. Li. IEEE Trans. ...

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2007

We present here preliminary results on boron diffusion in presence of pre-formed voids of differe... more We present here preliminary results on boron diffusion in presence of pre-formed voids of different characteristics. The voids were fabricated by helium implantation followed by annealing allowing the desorption of He prior to boron implantation. We show that under such conditions boron diffusion is always largely reduced and can even be suppressed in some cases. Boron diffusion suppression can be observed in samples not containing nanovoids in the boron-rich region. It is suggested that direct trapping of Si(int)s by the voids is not the mechanism responsible for the reduction of boron diffusion in such layers. Alternatively, our experimental results suggest that this reduction of diffusivity is more probably due to the competition between two Ostwald ripening phenomena taking place at the same time: in the boron-rich region, the competitive growth of extrinsic defects at the origin of TED and, in the void region, the Ostwald ripening of the voids which involves large supersaturations of Vs.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2011

ABSTRACT In this work, non-intentionally doped cubic silicon carbide (3C-SiC) epilayers grown on ... more ABSTRACT In this work, non-intentionally doped cubic silicon carbide (3C-SiC) epilayers grown on (100) silicon substrates were implanted using nitrogen (N), phosphorus (P) implantations or their co-implantation (N&amp;P). After annealing from 1150 to 1400°C, Secondary Ion Mass Spectroscopy (SIMS), Atomic Force Microscopy (AFM), Fourier Transformed InfraRed spectroscopy (FTIR), Scanning Spreading Resistance Microscopy (SSRM) and Scanning Transmission Electron Microscopy (STEM) analysis were performed. Specific contact resistances (ρc) of Ti/Ni ohmic contacts were determined using Circular Transfer Length Method (c-TLM) patterns. Our work shows that co-implantation, experimentally investigated for the first time in 3C-SiC, is not beneficial for the doping efficiency.According to the silicon substrate, the post-implantation annealing is limited to 1400°C. Consecutively to this limit, the total recovering of the lattice does not seem to be possible, whatever are the implanted species. Moreover, as the crystal damages increase when increasing the atomic mass of the implanted species, a comparative study using SSRM measurements proved that, for the same post-implantation annealing treatment, the resistivity of implanted layers depend on the doping species. As a consequence, the lowest ρc value (2.8×10−6Ωcm2) has been obtained (using Ti/Ni 25/100nm pattern) for a 1400°C–30min annealing consecutively to the nitrogen implantation. This value is among the best values obtained on implanted 3C-SiC layers in the literature. Furthermore, for this annealing temperature, a doping activation close to 100% has been evaluated by quantitative SSRM technique which evidences that an efficient dopant activation could be done. The high activation rate obtained on n-type implanted 3C-SiC and the low specific contact resistance achieved with Ti/Ni are very promising for electronic device fabrication.

Materials Science and Engineering: B, 2010

For electronic devices, good ohmic contacts are required. To achieve such contacts, the semicondu... more For electronic devices, good ohmic contacts are required. To achieve such contacts, the semiconductor layer has to be highly doped. The only method available to locally dope the SiC is to implant dopants in the epilayer through a mask. In this work, non-intentionally doped 3C-SiC epilayers were implanted using nitrogen or phosphorus at different energies and subsequently annealed at temperatures between 1150 • C and 1350 • C in order to form n + implanted layers. Different techniques such as Fourier Transformed InfraRed spectroscopy (FTIR), Secondary Ion Mass Spectroscopy (SIMS) and Transmission Electron Microscopy (TEM) were used to characterize implanted 3C-SiC epilayers subsequently to the different annealing steps. Then, Ti-Ni contacts were carried out and the specific contact resistance ( C ) was determined by using circular Transfer Length Method (c-TLM) patterns. C values were investigated as a function of implanted species and contact annealing conditions, and compared to those obtained for highly doped 3C-SiC epilayers. As expected, C value is highly sensitive to post-implantation annealing. This work demonstrates that low resistance values can be achieved using nitrogen or phosphorus implantation at room temperature hence enabling device processing.

Solid State Phenomena, 2004

Solid State Phenomena, 2005

Solid State Phenomena, 2008

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2012

Gallium nitride (GaN) is a promising material for power electronic devices. Due to GaN sensitivit... more Gallium nitride (GaN) is a promising material for power electronic devices. Due to GaN sensitivity to high temperature treatments, dopant activation, after ion implant, is one of the major critical steps to be overcome. An annealing cap layer is then mandatory during high temperature treatment to avoid degradations. In this work, cap layers, such as AlN and SiOx, were deposited

Nanoscale Research Letters, 2014

A perfect control of nanostructure growth is a prerequisite for the development of electronic and... more A perfect control of nanostructure growth is a prerequisite for the development of electronic and optoelectronic device/systems. In this article, we demonstrate the growth of various ZnO-derived nanostructures, including well-ordered arrays of high aspect ratio single crystalline nanowires with preferred growth direction along the [0001] axis, nanowalls, and hybrid nanowire-nanowall structures. The growths of the various ZnO nanostructures have been carried out on SiC substrates in a horizontal furnace, using Au thin film as catalyst. From experimental observations, we have ascribed the growth mechanisms of the different ZnO nanostructures to be a combination of catalytic-assisted and non-catalytic-assisted vapor-liquid-solid (VLS) processes. We have also found that the different ZnO nanoarchitectures' material evolution is governed by a Zn cluster drift effects on the SiC surface mainly driven by growth temperature. Au thin film thickness, growth time, and temperature are the parameters to optimize in order to obtain the different ZnO nanoarchitectures.

Materials Science Forum, 2009

... [2] T. Palacios, A. Chakraborty, S. Heikman, S. Keller, SP DenBaars, UK Mishra: IEEE Electron... more ... [2] T. Palacios, A. Chakraborty, S. Heikman, S. Keller, SP DenBaars, UK Mishra: IEEE Electron Device Letters Vol. 27 (2006), p. 13 [3] CP Chan, J. Gao, TM Yue, C. Ng. Surya, AB Djuric, PC-K. Liu, M. Li: IEEE Transactions on Electron Devices Vol. 53 (2006), p. 2266 ...

3C-SiC, the only polytype which can be heteroepitaxially grown on large diameter silicon substrat... more 3C-SiC, the only polytype which can be heteroepitaxially grown on large diameter silicon substrates, is a promising material to achieve power Schottky diodes. To carry out such diodes, high quality ohmic contacts are required. In this work, ohmic contacts were investigated on in situ highly n-doped 3C-SiC epilayers grown on (100) cheap silicon substrates. Different metals such as nickel, titanium, aluminum and gold were used to carry out the contacts. Classical circular Transfert Length Method (c-TLM) structures were prepared to evaluate the specific contact resistance. Ni and Ti-Ni contacts were annealed between 950°C and 1050°C while Al and Ti-Au contacts were annealed between 300°C and 600°C. The specific contact resistance was then determined by using c-TLM patterns. For each investigated contact, the best specific contact resistance values obtained are lower than 2x10 -5 Ω.cm 2 , even consecutively to a low temperature annealing.

physica status solidi (c), 2010

Materials Science Forum, 2010

During device manufacture, metal contamination has a large effect on silicon-based device perform... more During device manufacture, metal contamination has a large effect on silicon-based device performance. Of the available gettering techniques, helium implantation is widely used but the high fluence required is a major drawback. In this paper, the impact of F coimplantation on He implantation-induced defects has been carefully studied. Firstly, our results show that both interstitial and vacancy defects are present in the defect band for all implantation conditions. We show that F implantation may lead to cavity formation at high temperature as expected. The TEM observations also show that, at high temperature, the shape and size of the He-induced defects are significantly affected by the fluorine co-implantation. In particular, cavities are drastically modified by the addition of F, which promotes cavity growth. These results enable us to understand the defect interactions better and constitute a good background to gettering techniques for future device processing.

Solid State Phenomena, 2004

Solid State Phenomena, 2002

Metal contaminants, even at low concentration, are able to degrade the performance of silicon-bas... more Metal contaminants, even at low concentration, are able to degrade the performance of silicon-based devices. It has been shown that high dose helium implants in silicon, with a subsequent thermal anneal, produce cavities and dislocations, which are able to getter these impurities . However, most of the papers in the literature focus on the interaction between these cavities and the metal contaminants (Fe, Cu and Au) [1-4], they omit their interactions with dopants, which can be found in any devices with high concentrations compared with contamination level. The relation cavity layer-dopants can largely influence the structure through diffusion or segregation phenomena as well as the electrical activity of the components [4-5] and can become a drawback of this gettering technique. In this paper we will focus on the strong interaction between this layer and dopants (Boron and Phosphorus) in terms of dopant segregation. In this work, P and N-type <111> Si wafers, uniformly doped respectively with B and P with concentrations of about 3×10 18 cm -3 , were used. In this way, the initial dopant concentration was kept below the solid solubility. The helium implantation was performed using always the same conditions (40 keV and 5 ×10 16 cm -2 ) at room temperature. Furnace Annealing (FA) and Rapid Thermal Annealing (RTA), for various times ranging from 10s to 1h and temperatures in the range of 650°C up to 1000°C, were applied on the samples. Secondary Ion Mass Spectrometry (SIMS) was used to follow the dopant profile in the vicinity of the cavities as well as in the bulk, using conditions that prevented from such measurement artifacts. Spreading Resistance Profilometry (SRP) measurements, which allows us to determine the carrier concentration profiles, are presented. For better understanding, we used TEM measurements from previous work . We will enlighten, in this paper, the strong interaction between the cavity layer, induced by helium implantation, and both boron and phosphorus. After evidencing the impact of He gettering step on the dopant profile and in order to study the dopant-cavity layer interaction, we use uniformly N and P doped wafers implanted with helium at high dose and annealed using RTA and FA system. To avoid any precipitation phenomena, conditions were chosen not to exceed the dopant solid solubility value. Our experimental results exhibit a large trapping of both species within the cavity layer (see and 2) that occurs since the early stage of the annealing. SRP measurements clearly indicate the importance of the He post-implantation anneal to obtain a complete activation of the dopant (See . These results enable us to have better understanding of the effect of the He gettering step as well as its interaction with dopant atoms. Moreover, we will compare and discuss the impact of this stage on P and B doped layers. This is of great interest for present and future device fabrication.

MRS Proceedings, 2008

ABSTRACT The fabrication of highly doped and ultra-shallow junctions in silicon is a very challen... more ABSTRACT The fabrication of highly doped and ultra-shallow junctions in silicon is a very challenging problem for the materials scientist. The activation levels which are targeted are well beyond the solubility limit of current dopants in Si and, ideally, they should not diffuse during the activation annealing. In practice, the situation is even worse and when boron is implanted into silicon excess Si interstitial atoms are generated which enhance boron diffusion and favor the formation of Boron-Silicon Interstitials Clusters (BICs). An elegant approach to overcome these difficulties is to enrich the Si layers where boron will be implanted with vacancies before or during the activation annealing. Spectacular results have been recently brought to the community showing both a significant control over dopant diffusion and an increased activation of boron in such layers. In general, the enrichment of the Si layers with vacancies is obtained by Si+ implantation at high energy. We have recently developed an alternative approach in which the vacancies are injected from populations of empty voids undergoing Ostwald ripening during annealing. While different, the effects are also spectacular. The goal of this work is to establish a fair evaluation of these different approaches under technologically relevant conditions. The application domains of both techniques are discussed and future directions for their development/improvement are indicated.

Materials Science Forum, 2011

Materials Science Forum, 2012

In this paper, we studied the influence of nitrogen implantation dose on both physical and electr... more In this paper, we studied the influence of nitrogen implantation dose on both physical and electrical properties in 3C-SiC grown on Si (100) substrate. Scanning Transmission Electron Microscopy characterizations prove that high dose is responsible for amorphization of the implanted layer and the high defect density after annealing. A high V-shape defect density is still found in the implanted layer after an annealing at 1350°C. By lowering the dose, the layer is less damaged and no amorphization is observed. For the different doses, low Specific Contact Resistances are measured using Ti/Ni contacts. The Specific Contact Resistance value decreases from 8x10 -6 Ω.cm 2 for the high dose to 3.2x10 -6 Ω.cm 2 with decreasing the dose. Furthermore, the dopant activation ratio, evaluated by quantitative SSRM measurements, is improved at the same time from 17% (for the high dose) to 60% (for the low dose). This work demonstrates that high activation ratio can be achieved consecutively to a nitrogen implantation at reasonable implantation fluence.

Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2006

Dielectric function of disorder in single-crystalline silicon (c-Si) implanted by He with energy ... more Dielectric function of disorder in single-crystalline silicon (c-Si) implanted by He with energy of 40keV and fluences from 1×1016 to 1×1017cm−2 were determined around the E1 and E2 critical points (CPs) by spectroscopic ellipsometry. The implanted material was modeled by an effective medium composition of c-Si and damaged Si. The dielectric function of damaged Si was calculated using the model

physica status solidi (c), 2010

... IEEE Internat. 16.1.1 16.1.3 (2003). [5] T. Palacios, A. Chakraborty, S. Heikman, S. Keller, ... more ... IEEE Internat. 16.1.1 16.1.3 (2003). [5] T. Palacios, A. Chakraborty, S. Heikman, S. Keller, SP DenBaars, and UK Mishra. Electron Device Lett., IEEE 27(1), 13-15 (2006). [6] CP Chan, J. Gao, TM Yue, C.Ng. Surya, AB Djuric, PC-K. Liu, and M. Li. IEEE Trans. ...

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2007

We present here preliminary results on boron diffusion in presence of pre-formed voids of differe... more We present here preliminary results on boron diffusion in presence of pre-formed voids of different characteristics. The voids were fabricated by helium implantation followed by annealing allowing the desorption of He prior to boron implantation. We show that under such conditions boron diffusion is always largely reduced and can even be suppressed in some cases. Boron diffusion suppression can be observed in samples not containing nanovoids in the boron-rich region. It is suggested that direct trapping of Si(int)s by the voids is not the mechanism responsible for the reduction of boron diffusion in such layers. Alternatively, our experimental results suggest that this reduction of diffusivity is more probably due to the competition between two Ostwald ripening phenomena taking place at the same time: in the boron-rich region, the competitive growth of extrinsic defects at the origin of TED and, in the void region, the Ostwald ripening of the voids which involves large supersaturations of Vs.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2011

ABSTRACT In this work, non-intentionally doped cubic silicon carbide (3C-SiC) epilayers grown on ... more ABSTRACT In this work, non-intentionally doped cubic silicon carbide (3C-SiC) epilayers grown on (100) silicon substrates were implanted using nitrogen (N), phosphorus (P) implantations or their co-implantation (N&amp;P). After annealing from 1150 to 1400°C, Secondary Ion Mass Spectroscopy (SIMS), Atomic Force Microscopy (AFM), Fourier Transformed InfraRed spectroscopy (FTIR), Scanning Spreading Resistance Microscopy (SSRM) and Scanning Transmission Electron Microscopy (STEM) analysis were performed. Specific contact resistances (ρc) of Ti/Ni ohmic contacts were determined using Circular Transfer Length Method (c-TLM) patterns. Our work shows that co-implantation, experimentally investigated for the first time in 3C-SiC, is not beneficial for the doping efficiency.According to the silicon substrate, the post-implantation annealing is limited to 1400°C. Consecutively to this limit, the total recovering of the lattice does not seem to be possible, whatever are the implanted species. Moreover, as the crystal damages increase when increasing the atomic mass of the implanted species, a comparative study using SSRM measurements proved that, for the same post-implantation annealing treatment, the resistivity of implanted layers depend on the doping species. As a consequence, the lowest ρc value (2.8×10−6Ωcm2) has been obtained (using Ti/Ni 25/100nm pattern) for a 1400°C–30min annealing consecutively to the nitrogen implantation. This value is among the best values obtained on implanted 3C-SiC layers in the literature. Furthermore, for this annealing temperature, a doping activation close to 100% has been evaluated by quantitative SSRM technique which evidences that an efficient dopant activation could be done. The high activation rate obtained on n-type implanted 3C-SiC and the low specific contact resistance achieved with Ti/Ni are very promising for electronic device fabrication.

Materials Science and Engineering: B, 2010

For electronic devices, good ohmic contacts are required. To achieve such contacts, the semicondu... more For electronic devices, good ohmic contacts are required. To achieve such contacts, the semiconductor layer has to be highly doped. The only method available to locally dope the SiC is to implant dopants in the epilayer through a mask. In this work, non-intentionally doped 3C-SiC epilayers were implanted using nitrogen or phosphorus at different energies and subsequently annealed at temperatures between 1150 • C and 1350 • C in order to form n + implanted layers. Different techniques such as Fourier Transformed InfraRed spectroscopy (FTIR), Secondary Ion Mass Spectroscopy (SIMS) and Transmission Electron Microscopy (TEM) were used to characterize implanted 3C-SiC epilayers subsequently to the different annealing steps. Then, Ti-Ni contacts were carried out and the specific contact resistance ( C ) was determined by using circular Transfer Length Method (c-TLM) patterns. C values were investigated as a function of implanted species and contact annealing conditions, and compared to those obtained for highly doped 3C-SiC epilayers. As expected, C value is highly sensitive to post-implantation annealing. This work demonstrates that low resistance values can be achieved using nitrogen or phosphorus implantation at room temperature hence enabling device processing.