High-sensitivity uncooled InAsSb photoconductors with long wavelength were successfully fabricated. The detectors are based on InAsSb epilayers with the thickness of 100 µm grown on InAs substrates by melt epitaxy (ME). Si optical lenses were set on the photoconductors without any antireflective coatings. At room temperature, the peak detectivity Dλp* (6.5 µm, 1200) reaches 5.3 ×109 cm Hz1/2 W-1 for InAsSb immersion photoconductors. The detectivity D* at the wavelength of 8 µm is 1.5 ×108 cm Hz1/2 W-1, and that at 9 µm is 1.0 ×107 cm Hz1/2 W-1. The excellent performance of the detectors indicates the potential applications for infrared (IR) detection and imaging at room temperature.

Uncooled InAsSb Photoconductors with Long Wavelength

Antimonide based III–V materials have been attracting great attention as they have wide applications covering photodetection, light source, photovoltaics and electronic devices. In this paper, we report on the structural and optical properties and photodetection performance of an InAsSb layer grown on a GaSb substrate by molecular beam epitaxy (MBE). An x-Ray diffraction (XRD) study shows that the Lattice-mismatch between the GaSb substrate and the InAsSb epitaxial layer is about 0.17% and the derived composition of Sb is about 0.09. Photoluminescence measurements at varied temperatures reveal that the energy band gap of the InAsSb material is about 0.33 eV and the luminescence peaks follow Bose–Einstein relation. The photoconductors fabricated based on the InAsSb/GaSb structure show spectral response ranging from NIR to MWIR range. They can work well at low voltage bias and the measured blackbody detectivitives are ~2.4 × 107 cmHz1/2W−1 and ~6.1 × 109 cmHz1/2W−1 at room temperature and 77 K, respectively.

https://iopscience.iop.org/article/10.1088/0031-8949/91/11/115801/pdf

InAs 0.91 Sb 0.09 photoconductor for near and middle infrared photodetection

Effect of the Sb content and the n− and p−GaSb(100) substrates on the physical and chemical properties of InSbxAs1-x alloys for mid-infrared applications: Analysis of surface, bulk and interface

The charge carrier distribution profile, carrier dynamics, barrier height and conduction band offset for asymmetric InAs/InxGa1−x As/GaAs dot-in-well (DWELL) structures are evaluated from temperature-dependent electronic transport and spectroscopic measurements. The charge carrier leakages via defects lead to less charge carrier accumulation in the DWELL architecture in comparison with the associated QWs. Furthermore, the differential capacitance–voltage measurements show the resonance of charge carrier escape rate with the ground and excited states of the DWELL structure. The peak of the charge carrier escape rate related to the excited state is almost independent of the temperature while that of the ground state changes significantly with heating. It is explained on the basis of changes in the accumulated carrier density due to carrier localization and nonradiative recombination processes, via defects/dislocations/Auger recombination, which are dominant at moderate and high temperatures, respectively. Furthermore, the obtained values of barrier height and conduction band offsets for asymmetric InAs/InxGa1−x As/GaAs (x = 0.18) DWELL structures are 194 ± 10 meV and 287 ± 10 meV, respectively. Downward transitions from both ground and excited states of quantum dots (QDs) are observed in photoluminescence while upward transitions only to the excited state energy levels of QDs are observed in photoreflectance spectroscopy. This is due to the filling of the ground state energy levels of QDs, which is confirmed by the electron transport measurements. Hence, it is concluded that interband absorption occurs to the excited states, whereas intersubband absorption predominantly takes place from the ground states to the continuum of the QD ensemble.

https://iopscience.iop.org/article/10.1088/0022-3727/45/36/365104/pdf

Evaluation of electronic transport properties and conduction band offsets of asymmetric InAs/In x Ga 1−x As/GaAs dot-in-well structures

The influence of As molecular form on the composition and crystalline properties of InAsxSb1-x solid solutions with MBE has been experimentally investigated. A series of samples has been grown at different growth temperatures. The grown samples were studied with the HRXRD and TEM methods. The incorporation coefficient of As4 and As2 molecules were determined at different growth temperatures. It has been found that the incorporation coefficient of As4 much more dependent on growth temperature compared to As2. It has been found that at a low growth temperature a step-like increase of Sb fraction in an InAsxSb1-x film leads to a decrease of threading dislocations density in a layer with a smaller x.

https://iopscience.iop.org/article/10.1088/1742-6596/643/1/012006/pdf

InAsSb on GaAs (001): influence of the arsenic molecules form on composition and crystalline properties of MBE layers

InAsSb immersion photoconductors with a response wavelength range of 2–9 µm operated at room temperature were reported. The detectors are based on InAsSb single crystals grown on InAs substrates by melt epitaxy (ME). Van der Pauw measurements showed that the 300 K electron mobilities of InAsSb materials are higher than 5×104 cm2 V-1 s-1 with carrier densities of (1–3)×1016 cm-3. The photoconductors were measured using a standard blackbody source at a temperature of 500 K and a modulation frequency of 800 Hz under an applied bias current of 10 mA. At 293 K, the blackbody detectivity Dbb* (500 K, 800) reaches (2–6)×108 cm Hz1/2 W-1, indicating the high sensitivity of the detectors and their potential detection applications.

High-Sensitivity InAsSb Photoconductors with a Response Wavelength Range of 2–9 µm Operated at Room Temperature

High sensitivity uncooled InAsSb photoconductors with cutoff wavelengths longer than 8 mm were experimentally validated. The detectors were fabricated using InAs0.052Sb0.948 and InAs0.023Sb0.977 single crystals grown on InAs substrates by melt epitaxy (ME). The thickness of the epilayers was 50 mm. Ge optical lenses were set on the photoconductors. At room temperature, the photoresponse wavelength range was 2-10 m. Peak detectivity Dλp* (6.5 mm, 1200 Hz) reached 5.4 × 109 cm Hz1/2 W-1 for InAs0.052Sb0.948 immersed detectors. The detectivity D* was 9.3 × 108 and 1.3 × 108 cm Hz1/2 W-1 at the wavelength of 8 and 9 mm respectively. The good performances of InAsSb detectors indicate the possible detection applications

Xiu Ying Gong

Papers

High-Sensitivity InAsSb Photoconductors with a Response Wavelength Range of 2–9 µm Operated at Room Temperature

InAsSb Single Crystals and Photoconductors with Cutoff Wavelengths Longer than 8 µm

Improved performance of InAs0.07Sb0.93 photoconductors operating at room temperature