J. D. Kim

8-13 μm InAsSb heterojunction photodiode operating at near room temperature

p+‐InSb/π‐InAs1−xSbx/n+‐InSb heterojunction photodiodes operating at near room temperature in the 8–13 μm region of infrared (IR) spectrum are reported. A room‐temperature photovoltaic response of up to 13 μm has been observed at 300 K with an x≊0.85 sample. The voltage responsivity‐area product of 3×10−5 V cm2/W has been obtained at 300 K for the λ=10.6 μm optimized device. This was close to the theoretical limit set by the Auger mechanism, with a detectivity at room temperature of ≊1.5×108 cm Hz1/2/W.

LONG-WAVELENGTH INASSB PHOTOCONDUCTORS OPERATED AT NEAR ROOM TEMPERATURES (200-300 K)

Long‐wavelength InAs1−xSbx photoconductors operated without cryogenic cooling are reported. The devices are based on p‐InAs1−xSbx/p‐InSb heterostructures grown on (100) semi‐insulating GaAs substrates by low pressure metalorganic chemical vapor deposition (LP‐MOCVD). Photoreponse up to 14 μm has been obtained in a sample with x=0.77 at 300 K, which is in good agreement with the measured infrared absorption spectra. The corresponding effective lifetime of ≊0.14 ns at 300 K has been derived from stationary photoconductivity. The Johnson noise limited detectivity at λ=10.6 μm is estimated to be about 3.27×107 cm Hz1/2/W at 300 K.

Growth and characterization of InSbBi for long wavelength infrared photodetectors

The epitaxial growth of InSbBi ternary alloys by low-pressure metalorganic chemical vapor deposition is reported on. X-ray diffraction spectra showed well resolved peaks of InSbBi and InSb films. Bi incorporation was confirmed by energy dispersive x-ray analysis. Photoresponse spectrum up to 9.3 μm which corresponds to 0.13 eV energy band gap has been measured in a sample with Bi composition of 5.8 at.% at 77 K. Electron mobility at room temperature ranges from 44 100 to 4910 cm2/Vs as Bi composition increases.

InSb infrared photodetectors on Si substrates grown by molecular beam epitaxy

The InSb infrared photodetectors grown heteroepitaxially on Si substrates by molecular beam epitaxy (MBE) are reported. Excellent InSb material quality is obtained on 3-in Si substrates (with a GaAs predeposition) as confirmed by structural, optical, and electrical analysis. InSb infrared photodetectors on Si substrates that can operate from 77 K to room temperature have been demonstrated. The peak voltage-responsitivity at 4 /spl mu/m is about 1.0/spl times/10/sup 3/ V/W and the corresponding Johnson-noise-limited detectivity is calculated to be 2.8/spl times/10/sup 10/ cm/spl middot/Hz/sup 1/2//W. This is the first important stage in developing InSb detector arrays or monolithic focal plane arrays (FPAs) on silicon. The development of this technology could provide a challenge to traditional hybrid FPAs in the future.

The molecular beam epitaxial growth of InSb on (111)B GaAs

The molecular beam epitaxial growth of InSb on (111)B GaAs has been investigated. It was found that for a given Sb/In ratio, a higher growth temperature was required for the growth of InSb on (111)B GaAs compared to that on (001) GaAs. This difference has been attributed to the bonding characteristics of the (111)B and (001) surface. Once growth had been optimized, it was found that the material characteristics of (111)B InSb were almost identical to that of (001) InSb, i.e., independent of orientation. For example, the x‐ray full width at half‐maximum and 300 K mobility had the same absolute values for (111) InSb and (001)InSb and followed the same dependence with the sample thickness. Te was found to be a well‐behaved n‐type dopant for (111)B InSb.

Room temperature operation of 8–12 μm InSbBi infrared photodetectors on GaAs substrates

We report the room temperature operation of 8–12 μm InSbBi long-wavelength infrared photodetectors. The InSbBi/InSb heterostructures were grown on semi-insulating GaAs (001) substrates by low pressure metalorganic chemical vapor deposition. The voltage responsivity at 10.6 μm was about 1.9 mV/W at room temperature and the corresponding Johnson noise limited detectivity was estimated to be about 1.2×106 cmHz1/2/W. The carrier lifetime derived from the voltage dependent responsivity measurements was about 0.7 ns.

Room‐temperature operation of InTlSb infrared photodetectors on GaAs

Long‐wavelength InTlSb photodetectors operating at room temperature are reported. The photo‐ detectors were grown on (100) semi‐insulating GaAs substrates by low‐pressure metalorganic chemical vapor deposition. Photoresponse of InTlSb photodetectors is observed up to 11 μm at room temperature. The maximum responsivity of an In0.96Tl0.04Sb photodetector is about 6.64 V/W at 77 K, corresponding to a detectivity of about 7.64×108 cm Hz1/2/W. The carrier lifetime in InTlSb photodetectors derived from the stationary photoconductivity is 10–50 ns at 77 K.

HIGH CARRIER LIFETIME INSB GROWN ON GAAS SUBSTRATES

We report on the growth of near bulklike InSb on GaAs substrates by molecular beam epitaxy despite the 14% lattice mismatch between the epilayer and the substrate. Structural, electrical, and optical properties were measured to assess material quality. X-ray full widths at half-maximum were as low as 55 arcsec for a 10 μm epilayer, peak mobilities as high as ∼125 000 cm2/V s, and carrier lifetimes up to 240 ns at 80 K.

Long-wavelength infrared photodetectors based on InSbBi grown on GaAs substrates

We demonstrate the operation of InSbBi infrared photoconductive detectors grown by low-pressure metalorganic chemical vapor deposition on semi-insulating GaAs substrates. The fabricated photodetector showed a cutoff wavelength of 7.7 μm at 77 K. The responsivity of the InSbBi photodetector at 7 μm was about 3.2 V/W at 77 K. The corresponding Johnson-noise limited detectivity was 4.7×108 cm Hz1/2/W. The carrier lifetime was estimated to be about 86 ns from the voltage-dependent responsivity measurements.

Sb-based infrared materials and photodetectors for the 3-5 and 8-12 μm range

In this paper, we report on the growth of InSb on (100) Si and (111)B GaAs substrates and the growth of InAsSb alloys for longer wavelength applications. The fabrication and characterization of photodetectors based on these materials are also reported. Both photoconductive and photovoltaic devices are investigated. The photodiodes are InSb p-i-n structures and InSb/InAs1-xSbx/InSb double heterostructures grown on (100) and (111)B semi-insulating GaAs and Si substrates by low pressure metalorganic chemical vapor deposition and solid source molecular beam epitaxy. The material parameters for device structures have been optimized through theoretical calculations based on fundamental mechanisms. InSb p-i-n photodiodes with peak responsivities approximately 103 V/W were grown on Si and (111) GaAs substrates. An InAsSb photovoltaic detector with a composition of x equals 0.85 showed photoresponse up to 13 micrometers at 300 K with a peak responsivity of 9.13 X 10-2 V/W at 8 micrometers . The RoA product of InAsSb detectors has been theoretically and experimentally analyzed.