Electrical Properties of Midwave and Longwave InAs/GaSb Superlattices Grown on GaAs Substrates by Molecular Beam Epitaxy (original) (raw)
Related papers
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.
Transport measurements on InAs/GaSb superlattice structures for mid-infrared photodiode
Journal of Physics: Conference Series, 2009
In this communication, we report on electrical transport measurements of nonintentionally doped InAs/GaSb Superlattice structures grown by Molecular Beam Epitaxy. Resistivity and Hall Effect measurements were performed on two samples, corresponding to the same SL structure that has been grown on two different substrates: one on semi-insulating GaAs substrate, another on n-type GaSb substrate. To carry out the electrical measurements, the conducting GaSb substrate of the second sample has been removed. The study were performed in the temperature range 77-300K, for magnetic fields of 0.38 T.. The both samples exhibited a change in type of conductivity from p-type at low temperature to n-type near room temperature.
Infrared Physics & Technology, 2014
Herein, we report a type II InAs/GaSb superlattice structure (SLS) grown on GaSb (100) substrates by molecular beam epitaxy (MBE) and its electrical characterization for mid-wavelength infrared detection. A GaSb buffer layer was grown under optimized SLS growth conditions, which can decrease the occurrence of defects for similar pyramidal structures. The complications associated with these conditions include oxide desorption of the substrate, growth temperature of the SLS, the V/III ratio during superlattice growth and the shutter sequence. High-resolution X-ray diffraction (HRXRD) shows the sixth satellite peak, and the period of the SLS was 52.9 Å. The atomic force microscopy (AFM) images indicated that the roughness was less than 2.8 nm. High-resolution transmission electron microscopy (HRTEM) images indicated that the SLS contains few structural defects related to interface dislocations or strain relaxation during the growth of the superlattice layer. The photoresponse spectra indicated that the cutoff wavelength was 4.8 µm at 300 K. The SLS photodiode surface was passivated by a zinc sulfide (ZnS) coating after anodic sulfide.
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.
Electrical properties of short period InAs/GaSb superlattice
physica status solidi (c), 2007
Electrical properties in the temperature range between 80K and 300K of type-II short period InAs/GaSb superlattice (SL) photodiode are reported. Resistivity and Hall measurements have been carried out on a 300 periods unintentionally doped SL grown on semi-insulating GaAs substrate while capacitance-voltage and current-voltage measurements have been performed on the same SL structure elaborated on n-type GaSb substrate. Whatever the electrical investigations, the behaviour of the InAs/GaSb SL versus temperature exhibited a reproducible change in type of conductivity. The SL is n-type at high temperatures range with n(300K) = 6x10 16 cm -3 whereas it is p-type at low temperatures with p(100K) = 2x10 16 cm -3 . This versatile change in type of conductivity is attributed to the presence of inserted InSb layer at the InAs-GaSb interface.
Transport studies of MBE-grown InAs/GaSb superlattices
Opto-Electronics Review, 2010
We report on the results of transport studies of MBE-grown InAs/GaSb superlattices. We demonstrate that the in-plane mobility is limited by interface roughness scattering by showing that, as a function of InAs layer width L, the in-plane mobility behaves as μ ∝ L5.3, which closely follows the classic sixth power dependence expected from theory for interface-roughness-limited mobility. Fits to the mobility data indicate that, for one monolayer surface roughness, the roughness correlation length is about 35 Å. Next, we show that the in-plane carrier mobility in InAs/GaSb superlattices is inversely proportional to carrier density in n- and p-type samples, the result of screened interface roughness scattering.
Optical and structural characterization of InAs/GaSb superlattices
Journal of Applied Physics, 1997
InAs/GaSb superlattices sandwiched between conventional InAs layers were grown by low pressure metal organic chemical vapor deposition. Period and roughness of the superlattices were examined by field emission transmission electron microscopy. Room temperature infrared absorption spectra for InAs/GaSb superlattices were obtained by Fourier-transform infrared spectroscopy. The effects of varying the doping levels and thicknesses of the InAs sandwiching layers on the absorption spectra of InAs/GaSb superlattices were studied. It was found that by choice of suitable doping levels and cap/buffer thicknesses, the resulting fermi level equalization (as in normal homo or heterojunctions) thereby allowed the setting or “pinning” of the superlattice Fermi level to any desired value within the range made available by the original bulk material characteristics in conjunction with the doping conditions. When the thicknesses of the InAs sandwiching layers became less than 1 μm, the sandwiching effect and the intersubband transition decreased dramatically. The structure of the interfaces inside the superlattice was also studied. Energy dispersive spectroscopy was used to estimate interdiffusion conditions within the superlattice. The effects of different periods and purge gases on the absorption spectra were also studied.