Growth and electrical characterization of type II InAs/GaSb superlattices for midwave infrared detection (original) (raw)
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MBE growth and characterization of type-II InAs/GaSb superlattices for mid-infrared detection
Journal of Crystal Growth, 2005
Type-II InAs/GaSb superlattices (SLs) made of 10 InAs monolayers (MLs) and 10 GaSb MLs, designed to have a cut-off wavelength of 5.4 mm, have been grown on GaSb substrates by solid source molecular beam epitaxy (MBE). In order to obtain lattice-matched structures, a thin layer of InSb was inserted at the GaSb on InAs interface. We demonstrate that structural and optical properties of such structures strongly depend on the thickness of the InSb inserted layer. Strain-balanced InAs/GaSb SLs could be grown, after optimizing the MBE shutter sequence, by using a growth temperature of 390 1C and an inserted InSb layer of thickness 1 ML. Non-optimized pin diodes using 100 periods of such an SL as absorbing material showed an absorption coefficient varying from 4 Â 10 3 to 6 Â 10 3 cm À1 at room temperature in the 3-5 mm mid-infrared wavelength region, and a photovoltaic response up to 230 K. r
Short-period InAs/GaSb superlattices for mid-infrared photodetectors
physica status solidi (c), 2007
Using a newly developed envelope function approximation model that includes interface effects, several InAs/GaSb type-II superlattices (SLs) were designed for uncooled mid-infrared detector applications. The 4 micron cutoff could be achieved with several SL designs. Superlattices with shorter periods have larger intervalence band separations than larger-ones, which could increase the optical signal and reduce the detector noise, thus making room temperature operation possible. To test these possibilities, several shortperiod SLs were grown by molecular-beam epitaxy and their optical properties with reducing SL period were studied by band-edge absorption, photoconductivity and photoluminescence measurements.
Characterization of midwave infrared InAs/GaSb superlattice photodiode
Journal of Applied Physics, 2009
We report on structural, electrical, and optical characterizations of midwave infrared InAs/GaSb superlattice ͑SL͒ p-i-n photodiodes. High-quality SL samples, with 1 m thick active region ͑220 SL periods͒, exhibited a cut-off wavelength of 4.9 m at 80 K. Using a capacitance-voltage measurement technique performed on mesa diode, the residual background concentration in the nonintentionally doped region was determined to be 3 ϫ 10 15 cm −3 at 80 K. Extracted from current-voltage characteristics, R 0 A products above 4 ϫ 10 5 ⍀ cm 2 at 80 K were measured, and the quantitative analysis of the J-V curves showed that the dark current density of SL photodiode is dominated by generation-recombination processes. Front-side illuminated photodiodes produced responsivity at 80 K equal to 360 mA/W at 4.5 m.
Interface analysis of InAs/GaSb superlattice grown by MBE
(2007) Journal of Crystal Growth, 301-302 (SPEC. ISS.), pp. 889-892.
We report on the structural characterization of short period type-II InAs/GaSb superlattices (SLs) adapted for mid-infrared detection. These structures, grown by molecular beam epitaxy (MBE) on n-type GaSb substrates, are made up of 10 InAs monolayers (MLs) and 10 GaSb MLs and a strain balanced condition is obtained by inserting an InSb ML at the interface between InAs and GaSb in each superlattice's period. From cross-sectional transmission electron microscopy (TEM) measurements, the interface structure is analysed in detail. Very homogeneous and smooth InAs and GaSb layers all over a 50 periods SL structure are observed and high-resolution images bring out the InSb ML inserted between InAs and GaSb. Room temperature absorbance spectroscopy measurements have been performed on strain-compensated SLs including 50, 100, 300 and 400 periods, for a total absorption zone thickness of 0.32, 0.64, 1.92 and 2.56 μm, respectively. The spectra display reproducible and well-defined features with an absorption coefficient varying between 2×10 3 and 4×10 3 cm -1 in the 3-5 μm mid-infrared domain, a sign of high-quality samples suitable for detection.
International Conference on Space Optics — ICSO 2018
We studied Ga-free InAs/InAsSb type-II superlattice (T2SL) in terms of period, thickness and antimony composition as a photon absorbing active layer (AL) of a suitable XBn structure for full mid-wavelength infrared domain (MWIR, 3-5µm) detection. The SL photodetector structures were fabricated by molecular beam epitaxy (MBE) on n-type GaSb substrate and exhibited cutoff wavelength between 5µm and 5.5µm at 150K. Electro-optical and electrical results of the device are reported and compared to the usual InSb MWIR photodiode.
High-performance InAs/GaSb superlattice photodiodes for the very long wavelength infrared range
Applied Physics Letters, 2001
We report on the demonstration of high-performance p-in photodiodes based on type-II InAs/ GaSb superlattices with 50% cutoff wavelength c ϭ16 m operating at 80 K. Material is grown by molecular beam epitaxy on GaSb substrates with excellent crystal quality as evidenced by x-ray diffraction and atomic force microscopy. The processed devices show a current responsivity of 3.5 A/W at 80 K leading to a detectivity of ϳ1.51ϫ10 10 cmHz 1/2 /W. The quantum efficiency of these devices is about 35% which is comparable to HgCdTe detectors with a similar active layer thickness.
Physica E: Low-dimensional Systems and Nanostructures, 2005
Type-II InAs (N) /GaSb (N) superlattices (SLs) where the SL's period is composed by equal number N of InAs and GaSb monolayers (MLs) have been grown by solid source molecular beam epitaxy on n-type GaSb substrate. These SLs are made up of 100 periods with a number of MLs varying from N ¼ 5 to 15. Photoluminescence and photoresponse measurements, performed at 80 K, displayed peak positions and cut-off wavelengths between 3.8 and 8.3 mm. These results are in good agreement with a modified envelope function approximation model taking into account a strong perturbative potential at each InAs/GaSb interface. P-i-n photodetectors, made-up from strain-compensated InAs (10) / GaSb (10) undoped superlattice, showed a cut-off wavelength at 5.6 mm, an absorption coefficient value varying from 4 Â 10 3 to 5.5 Â 10 3 cm À1 in the 3-5 mm wavelength range, and a photovoltaic response up to 260 K. r
Novel etch studies and passivation techniques on InAs/GaSb superlattice based infrared detectors
2013
Infrared (IR) detectors today are being utilized for a variety of imaging applications such as medical diagnostics, navigation instruments of automobiles and aircrafts, meteorological imaging, night-vision and fog/smoke imaging, surveillance, target acquisition and astronomical/space imaging. These wide ranging implementations have given rise to varied design requirements for these devices such as the required sensitivity, operating temperature, spectral sensitivity, peak wavelength and cost. Type-II band aligned InAs/Ga(In)Sb strained layer superlattice (SLS) material system proposed for the IR detection in the 1970s has been considered in recent years as an interesting alternative to the present day IR detection technologies. Type-II SLS technology possesses mature growth technologies able to achieve uniformity over large areas along with band-gap tunability which results in IR detectors in mid wave (MW), long-wave (LW) and
Growth and characterization of InAs/GaSb photoconductors for long wavelength infrared range
Applied Physics Letters, 1997
In this letter we report the molecular beam epitaxial growth and characterization of InAs/GaSb superlattices grown on semi-insulating GaAs substrates for long wavelength infrared detectors. Photoconductive detectors fabricated from the superlattices showed photoresponse up to 12 m and peak responsivity of 5.5 V/W with Johnson noise limited detectivity of 1.33ϫ10 9 cm Hz 1/2 /W at 10.3 m at 78 K. © 1997 American Institute of Physics. ͓S0003-6951͑97͒03236-1͔