High-frequency photovoltaic ISB detectors in the near- and mid-IR (original) (raw)

Analytical Simulation of an InAsSb Photovoltaic Detector for Mid-Infrared Applications

Abstract A generic model of a mid-infrared photodetector based on a narrow bandgap semiconductor has been developed. The model has been applied for analysis and simulation of an InAs0.89Sb0.11 photovoltaic detector for operation at room temperature in 2–5 mm wavelength region. The model takes into account the effect of tunneling and other components of dark current on the detectivity of the device by considering all the three dominant recombination mechanisms e.g., radiative, Shockley–Read–Hall and Auger recombination. The study revealed that the dark current of the photodetector under reverse bias is dominated by trap-assisted tunneling component of current and this causes the detectivity of the device to decrease at high reverse bias. It is further concluded that by operating the device at a suitable low reverse bias it is possible to improve the room-temperature detectivity significantly as compared to its value at zero bias.

Extension of longwavelength IR photovoltaic detector operation to near room-temperatures

Infrared Physics & Technology, 1995

Practical realization of near room temperature (230-300 K) longwavelength (5-12 tam) photovoltaic detectors is reported. The devices are epitaxial n+ipp photodiodes operated at ambient temperature or with a simple, two-stage thermoelectric cooling. The performance of the photodiodes has been improved by the use optimized composition and doping profile structures. The tunnel currents were minimized by interfacing the n + and p-type layers with a thin (0.5 lam) lightly doped i-region. The quantum efficiency has been increased by the use of backside reflector. Further improvement of performance was achieved by the use of monolithic optical immersion. Large area devices with useful performance were obtained by the use of small close-spaced elements connected in series. The near room temperature photovoltaic detectors are of particular significance for very low and very high frequency applications.

GaN/AlGaN heterojunction infrared detector responding in 8–14 and 20–70

2006

A GaN / AlGaN heterojunction interfacial work function internal photoemission infrared detector responding in 8-14 and 20-70 m ranges has been demonstrated. Free carrier absorption based photoresponse shows a wavelength threshold of 14 m with a peak responsivity of 0.6 mA/ W at 80 K under −0.5 V bias. A sharp peak in the 11-13.6 m range is observed superimposed on the free carrier response. In addition, the work demonstrates 54 m ͑5.5 THz͒ operation of the detector based on 1s-2p± transition of Si donors in GaN. Possible approaches on improving the performance of the detector are also addressed.

Performance improvements of ultraviolet/infrared dual-band detectors

Infrared Physics & Technology, 2007

Results are reported on dual-band detectors based on a GaN/AlGaN structure operating in both the ultraviolet-midinfrared (UV-MIR) and ultraviolet-farinfrared (UV-FIR) regions. The UV detection is due to an interband process, while the MIR/FIR detection is from free carrier absorption in the emitter/contact followed by internal photoemission over the barrier at the GaN/AlGaN interface. The UV detection, which was observed from 300 K to 4.2 K, has a threshold of 360 nm with a peak responsivity of 0.6 mA/W at 300 K. The detector shows a free carrier IR response in the 3-7 lm range up to 120 K, and an impurity response around 54 lm up to 30 K. A response in the range 7-13 lm, which is tentatively assigned to transitions from C impurities and N vacancies in the barrier region, was also observed. It should also be possible to develop a detector operating in the UV-visible-IR regions by choosing the appropriate material system. A dual-band detector design, which allows not only to measure the two components of the photocurrent generated by UV and IR radiation simultaneously but also to optimize the UV and IR responses independently, is proposed.

High-speed InSb photodetectors on GaAs for mid-IR applications

IEEE Journal of Selected Topics in Quantum Electronics, 2004

We report p-i-n type InSb-based high-speed photodetectors grown on GaAs substrate. Electrical and optical properties of photodetectors with active areas ranging from 7.06 10 6 cm 2 to 2.25 10 4 cm 2 measured at 77 K and room temperature. Detectors had high zero-bias differential resistances, and the differential resistance area product was 4.5 cm 2 . At 77 K, spectral measurements yielded high responsivity between 3 and 5 m with the cutoff wavelength of 5.33 m. The maximum responsivity for 80-m diameter detectors was 1.00 10 5 V/W at 4.35 m while the detectivity was 3.41 10 9 cm Hz 1 2 W. High-speed measurements were done at room temperature. An optical parametric oscillator was used to generate picosecond full-width at half-maximum pulses at 2.5 m with the pump at 780 nm. 30-m diameter photodetectors yielded 3-dB bandwidth of 8.5 GHz at 2.5 V bias.

High operating temperature split-off band infrared detectors

Applied Physics Letters, 2006

Heterojunction interfacial work function internal photoemission detectors were used to demonstrate infrared response originating from hole transitions between light/heavy hole bands and the split-off ͑spin-orbit͒ band. A GaAs/ AlGaAs heterojunction with a threshold wavelength of ϳ20 m indicated an operating temperature of 130 K for split-off response in the range of 1.5-5 m with a peak D * of 1.0ϫ 10 8 Jones. Analysis suggests that practical devices with optimized parameters are capable of achieving room temperature operation with higher specific detectivity. Possible approaches to tailor the threshold for the split-off response to different wavelength ranges using different materials such as phosphides and nitrides are also discussed.

Effects of a p–n junction on heterojunction far infrared detectors

Infrared Physics & Technology, 2007

HEterojunction Interfacial Workfunction Internal Photoemission (HEIWIP) far infrared detectors based on the GaAs/AlGaAs material system have shown promise for operation at wavelengths up to a few hundred microns. HEIWIP detectors with GaAs emitters have been shown to operate out to 92 lm. Recent modifications to use AlGaAs emitters have extended the zero response threshold out to 128 lm. Extension to longer wavelengths will require reducing the dark current in the devices. An approach using the addition of a p-n junction in the detector, which was shown to work in QWIP and homojunction detectors is considered here. Differences between the predicted and observed threshold behavior could be explained by the presence of space charge within the device. The band bending from this space charge produces the observed variation in the threshold. The space charge can also be used to explain anomalous conduction observed at low biases. When the device is forward biased, the current is expected, to be small until the bias voltage is similar to the bandgap of 1.4 eV, above which the current should increase rapidly. Dark current was observed for biases significantly less than the bandgap. The threshold bias decreased with temperature, and was as low as 0.25 V for a temperature of 300 K. This is much lower than could be explained by thermal effects alone.

Optimisation of InGaAs infrared photovoltaic detectors

IEE Proceedings - Optoelectronics, 1999

The ultimate signal-to-noise performance of infrared photodetectors is limited by the statistical nature of the thermal generation and recombination of charge carriers. Band-to-band Auger processes dominate in a high quality InGaAs used for photovoltaic detector operating at room temperature. The performance of devices operating in the 2-3.4pm spectral range has been analyzed theoretically. Homo-and heterostructure devices have been considered. The use of n+np+ (or n+pp+) with heavily doped regions has been found to prevent the recombination of photogenerated carriers at contacts, but the bulk thermal generation in the heavily doped regions will significantly reduce the performance of the devices.

Mid-wavelength infrared p-on-n Hg 1−x Cd x Te heterostructure detectors: 30–120 kelvin state-of-the-Art performance

Journal of Electronic Materials, 2003

We report on Hg1−xCdxTe mid-wavelength infrared (MWIR) detectors grown by molecular-beam epitaxy (MBE) on CdZnTe substrates. Current-voltage (I-V) characteristics of HgCdTe-MWIR devices and temperature dependence of focal-plane array (FPA) dark current have been investigated and compared with the most recent InSb published data. These MWIR p-on-n Hg1−xCdxTe/CdZnTe heterostructure detectors give outstanding performance, and at 68 K, they are limited by diffusion currents. For temperatures lower than 68 K, in the near small-bias region, another current is dominant. This current has lower sensitivity to temperature and most likely is of tunneling origin. High-performance MWIR devices and arrays were fabricated with median RoA values of 3.96 × 1010 Ω-cm2 at 78 K and 1.27 × 1012 Ω-cm2 at 60 K; the quantum efficiency (QE) without an antireflection (AR) coating was 73% for a cutoff wavelength of 5.3 µm at 78 K. The QE measurement was performed with a narrow pass filter centered at 3.5 µm. Many large-format MWIR 1024 × 1024 FPAs were fabricated and tested as a function of temperature to confirm the ultra-low dark currents observed in individual devices. For these MWIR FPAs, dark current as low as 0.01 e−/pixel/sec at 58 K for 18 × 18 µm pixels was measured. The 1024 × 1024 array operability and AR-coated QE at 78 K were 99.48% and 88.3%, respectively. A comparison of these results with the state-of-the-art InSb-detector data suggests MWIR-HgCdTe devices have significantly higher performance in the 30–120 K temperature range. The InSb detectors are dominated by generation-recombination (G-R) currents in the 60–120 K temperature range because of a defect center in the energy gap, whereas MWIR-HgCdTe detectors do not exhibit G-R-type currents in this temperature range and are limited by diffusion currents.

InSb Mid-Infrared Photon Detector for Room-Temperature Operation

Japanese Journal of Applied Physics, 2013

We developed a small InSb mid-infrared (2-7 m wavelength range) photon detector that operates at room temperature. The photodiode was made from (hetero epitaxial) InSb layers that were grown on a semi-insulating GaAs substrate by molecular beam epitaxy. To suppress the effects of the diffusion current of the p-in photodiode, we used an AlInSb barrier layer that raises the resistance of the photodiode. We also optimized the device's doping concentration and the infrared incidence window structure. These optimization steps realized high photoelectric current output in a room-temperature environment. We also increased the signal-to-noise ratio of the detector by connecting multiple photodiodes in series. The size of this detector is 1:9 Â 2:7 Â 0:4 mm 3 and the detectivity is 2:8 Â 10 8 cm Hz 1=2 /W at 300 K. This is a practical IR detector that can be used in general signal amplification ICs.

Intrinsic infrared detectors

Progress in Quantum Electronics, 1988

Notation 88 1. Introduction 89 2. Semiconductor Detectors 2.1. General classification of infrared detectors 2.2. Photon noise and fundamental limits 2.3. Photoconductive detectors 2.3.1. Photoconductivy theory 2.3.2. Noise mechanisms in photoconductors 2.3.3. Quantum efficiency 2.3.4. Ultimate detectivity of infrared photoconductors 2.35. Sweep-out effects 2.3.6. Influence of background 2.3.7. Influence of surface recombination 2.4. Photovoltaic detectors 2.4.1. Photovoltaic effect 2.4.2. Dark current in p-n junctions 2.4.3. Photocurrent in p-n junctions and quantum efficiency 2.4.4. R, A product 91 91 94 95 95 97 97 98 100 102 2.45. Noise mechanisms in photodiodes 2.4.6. Detectivity 2.4.7. Response time 2.4.8. Schottky barrier photodiodes 2.5. MIS devices 2.51. General MIS theory 2.52. Charge transfer devices in focal plane technology 2.53. Performance of focal plane arrays 2.6. Photoelectromagnetic detectors 2.6.1.

Infrared detectors: Advances, challenges and new technologies

IOP Conference Series: Materials Science and Engineering, 2013

Human knowledge of infrared (IR) radiation is about 200 years old. However it was in the late 20th century that we developed a wide range of smart technologies for detection and started to take advantage for our benefit. Today IR detector technology is in its 3rd generation and comes with challenging demands. Based on the propagation of IR radiation through free space it is divided into different transmission windows. The most interesting for thermal imaging are the mid-wave IR (MWIR) and the long-wave IR (LW IR). Infrared detectors for thermal imaging have a number of applications in industry, security, search & rescue, surveillance, medicine, research, meteorology, climatology and astronomy. Currently high-performance IR imaging technology is mainly based on epitaxially grown structures of the small-bandgap bulk alloy mercury-cadmiumtelluride (MCT), indium antimonide (InSb) and GaAs based quantum-well infrared photodetectors (QWIPs), depending on the application and wavelength range. However, they operate at low temperatures requiring costly and bulky cryogenic systems. In addition there is always a need for better performance, which generates possibilities for developing new technologies. Some emerging technologies are quantum dot infrared photodetectors (QDIPs), type-II strained layer super-lattice, and QDIPs with type-II band alignment. In this report a brief review of the current and new technologies for high performance IR detectors, will be presented. 10 µm. Whereas, the surface of the sun (~6000 K) has a peak emission in the visible range containing a great amount of IR and ultraviolet (UV) radiation.

Characterization of InGaSb detectors for 1.0- to 2.4-μm applications

Infrared Technology and Applications XXX, 2004

Near infrared detectors in the 1 to 2.4 µm spectral range are important for many applications such as atmospheric remote sensing, where several species have strong absorption spectra in that range. Antimonide-based III-V compound semiconductor materials are good candidates for developing detectors in that spectral range. Electrical and optical characteristics of In 1-x Ga x Sb p-n photodetectors at different temperatures are presented. The devices were fabricated either on bulk InGaSb substrates by zinc diffusion or InGaSb epitaxial layers grown on GaSb substrates by organo-metallic vapor phase epitaxy (OMVPE). Variable area devices were fabricated. Current-voltage measurements indicated higher dark current in InGaSb devices grown on GaSb substrate, due to defects generated by the latticemismatch. Spectral response measurements were obtained in the 1 to 2.4 µm wavelength range at different temperatures. At room temperature, the cutoff wavelengths were observed at 2.3 and 2.1 µm for InGaSb devices grown on GaSb and for devices fabricated on bulk InGaSb substrates respectively. Reducing the operating temperature shifts the cutoff wavelength to shorter values and increases the responsivity. Noise calculations indicated a room temperature detectivities of 3.3x10 10 and 5.5x10 10 cmHz 1/2 /W at 2 µm for the GaSb and InGaSb respectively. Detectivity variation with wavelength will be presented and compared to the background limited performance.

High sensitivity InAs photodiodes for mid-infrared detection

Electro-Optical Remote Sensing X, 2016

Sensitive detection of mid-infrared light (2 to 5 µm wavelengths) is crucial to a wide range of applications. Many of the applications require high-sensitivity photodiodes, or even avalanche photodiodes (APDs), with the latter generally accepted as more desirable to provide higher sensitivity when the optical signal is very weak. Using the semiconductor InAs, whose bandgap is 0.35 eV at room temperature (corresponding to a cutoff wavelength of 3.5 µm), Sheffield has developed high-sensitivity APDs for mid-infrared detection for one such application, satellite-based greenhouse gases monitoring at 2.0 µm wavelength. With responsivity of 1.36 A/W at unity gain at 2.0 µm wavelength (84 % quantum efficiency), increasing to 13.6 A/W (avalanche gain of 10) at-10V, our InAs APDs meet most of the key requirements from the greenhouse gas monitoring application, when cooled to 180 K. In the past few years, efforts were also made to develop planar InAs APDs, which are expected to offer greater robustness and manufacturability than mesa APDs previously employed. Planar InAs photodiodes are reported with reasonable responsivity (0.45 A/W for 1550 nm wavelength) and planar InAs APDs exhibited avalanche gain as high as 330 at 200 K. These developments indicate that InAs photodiodes and APDs are maturing, gradually realising their potential indicated by early demonstrations which were first reported nearly a decade ago.

Progress in Infrared Photodetectors Since 2000

Sensors, 2013

The first decade of the 21st-century has seen a rapid development in infrared photodetector technology. At the end of the last millennium there were two dominant IR systems, InSb-and HgCdTe-based detectors, which were well developed and available in commercial systems. While these two systems saw improvements over the last twelve years, their change has not nearly been as marked as that of the quantum-based detectors (i.e., QWIPs, QDIPs, DWELL-IPs, and SLS-based photodetectors). In this paper, we review the progress made in all of these systems over the last decade plus, compare the relative merits of the systems as they stand now, and discuss where some of the leading research groups in these fields are going to take these technologies in the years to come.

Long-wavelength interband cascade infrared photodetectors operating above room temperature

Quantum Sensing and Nanophotonic Devices XII, 2015

We report on a comparison study of long wavelength infrared interband cascade infrared photodetectors (ICIPs) with the goal of an improved understanding that will lead to further increases in the operation temperature. We studied four sets of detectors including single absorber barrier detectors and multi-stage ICIPs with four, six, and eight discrete absorbers. The 90% cutoff wavelength of these detectors was between 7.5 and 11.5 lm from 78 to 340 K. Multiple stage ICIPs were able to operate with monotonically increasing bias-independent responsivity up to 280 K, while the responsivity of the one-stage detectors decreased at 200 K with bias dependence. The advantages of the multi-stage ICIPs over the one-stage device are demonstrated in terms of lower dark current density, higher detectivity (D*), and higher operating temperatures. The onestage detectors operated at temperatures up to 250 K, while the ICIPs were able to operate up to 340 K with D* higher than 1.0 Â 10 8 cmÁHz 1/2 /W at 300 K. The D* for these ICIPs at 200 K was larger than 1.0 Â 10 9 cmÁHz 1/2 /W at 8 lm, which is more than a factor of two higher than the corresponding value for photovoltaic HgCdTe detectors at similar cutoff wavelengths. Interestingly, negative differential conductance (NDC) was observed in these detectors at high temperatures. The underlying physics of the NDC was investigated and correlated with the number of cascade stages and electron barriers. With the enhancement of the electron barrier in the multiple-stage ICIPs, the NDC was reduced, and the overall device performance, in terms of D*, was improved.

Modeling and optimization of InGaAs infrared photovoltaic detectors

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2000

The performance of In V Ga \V As detectors operating in the 2}3.4 m spectral range and temperature of 300 K has been analyzed theoretically as a function of wavelength, band gap and doping level with special emphasis on 2}2.5 m and 3}3.5 m atmospheric window devices. The calculations show that the dominant generation}recombination mechanism in p-type, intrinsic and in a lightly doped n-type InGaAs is the spin split-o! band Auger process (AS). Since the AS generation increases with the square of the hole concentration, the minimum thermal generation and the best performance can be obtained using moderately doped n-type material as the absorber region of a photovoltaic device. In principle, the ultimate performance can be achieved in the optimized homojunction devices with relatively thick n-type absorber region forming n}p junction with a thin p-type material. N-type doping of absorber region of InGaAs photodiodes at 300 K changes from 1;10 to 5.2;10 cm\ for devices optimized for operation at 2 and 3.4 m wavelength, respectively.

Infrared detectors: an overview

The paper presents progress in infrared (IR) detector technologies during 200 history of their development. Classification of two types of IR detectors (photon detectors and thermal detectors) is done on the basis of their principle of operation. The overview of IR systems and detectors is presented. Also recent progress in different IR technologies is described. Discussion is focused mainly on current and the most rapidly developing detectors: HgCdTe heterostructure photodiodes, quantum well AlGaAs/GaAs photoresistors, and thermal detectors. The outlook for near-future trends in IR technologies is also presented. Ó

Near- and far-infrared p‐GaAs dual-band detector

Applied Physics Letters, 2005

A dual-band homojunction interfacial workfunction internal photoemission infrared detector that responds in both near-and far-infrared ͑NIR and FIR͒ regions is reported. In the p +-i-p + detector structure, the emitter is carbon doped to 1.5ϫ 10 19 cm −3 , and a 1 m thick GaAs layer acts as the barrier, followed by another highly p-doped GaAs contact layer. The NIR response is due to the interband transition in GaAs barrier layer and the threshold wavelength observed at 0.82 m is in good agreement with the 1.51 eV band gap of GaAs at 4.2 K. The intraband transition giving rise to FIR response is observed up to 70 m. Interband responsivity was ͑under 100 mV reverse bias at 20 K͒ ϳ8 A / W at 0.8 m, while the intraband responsivity was ϳ7 A / W. The detector has peak detectivities D * ϳ 6 ϫ 10 9 and 5 ϫ 10 9 cm Hz 1/2 / W at 0.8 and 57 m wavelengths, respectively, under 100 mV reverse bias at 20 K.

Theoretical analysis of a proposed InAs/InAsSb heterojunction photodetector for mid-infrared (MIR) applications

Abstract: The authors propose a single heterojunction InAs/InAsSb photovoltaic detector for application in the mid-infrared region at room temperature. A closed form physics-based analytical model of the device has been developed for characterisation of the device. Numerical computations have been carried out on the basis of the model for a Pþ-InAs=n0-InAs0:88Sb0:12=nþ-InAs0:88Sb0:12 heterojunction photodetector to explore the potential of the device for possible non-telecommunication applications in the 2:5–4:5 mm wavelength region. The present model takes into account the effects of radiative recombination, Auger recombination, surface recombination and tunnelling at the hetero-interface on the detectivity of the device. The model enables the performance of the device to be optimised in terms of detectivity, responsivity and quantum efficiency. The model also provides useful design guidelines for fabrication of single heterojunction InAsSb photovoltaic detectors grown on InAs substrates. It has been observed that the doping concentration in the lightly doped active region, surface recombination and tunnelling at the hetero-interface strongly influence the performance of the InAs=InAs0:88Sb0:12 detectors.