Short period InAs/GaSb superlattice infrared detector on GaAs substrates

Two type II superlattices (SLs): InAs(2ML)/GaSb(8ML) and InAs(8ML)/GaSb(8ML) were grown on GaAs substrates by molecular-beam epitaxy. High resolution X-ray diffraction showed the periods of the two SLs were 31.2A(ngstrom) and 57.3A(ngstrom), respectively. Room-temperature optical transmittance spectra showed that there were clear absorption edges at 2.1 mum and 5 mum for the two SLs. The SWIR and MWIR photoconductor devices were fabricated by standard lithography and etched by tartaric acid solution. The spectral response and blackbody tests were carried out at low and room temperatures. The results show that the 50% cutoff wavelengths of the two photoconductors are 2.1 mum and 5.0 mum respectively and D(bb)* is above 2x10(8) cmHz(1/2)/W for two kinds of photoconductors at 77 K. D(bb)* is above 10(8) cmHz(1/2)/W for SWIR photoconductor at room temperature.