Structure And Properties Of InAs/GaSb Strain Superlattice Materials

Due to it's special band structure, InAs / Ga (In) SbⅡtype superlattice material has a broad prospect in LWIR and VLWIR region, and is expected to become the substitution of HgCdTe. To InAs / Ga (In) SbⅡtype superlattice materials, the research on interface effects have become one of the hotspot.In this paper we have studied the technology of epitaxy InAs / GaSb superlattice materials on the GaAs (100) substrates by MBE. We obtained a better polytechnic para- meters to growth InAs / GaSb superlattice materials: GaAs buffer layer growth temperature is 600℃, GaSb buffer layer growth temperature is 520℃, InAs / GaSb superlattice growth temperature is 400℃. As / In beam ratio is 4.5, Sb / Ga beam ratio is 6. On this basis, sample 1#,2#and3# with the structure designed as : {InAs(17ML)/InSb(0.5ML)/GaSb(13ML)}×30,{InAs(17ML)/InSb(1.0ML)/GaSb(13 ML)}×30,{InAs(8ML)/ InSb(0.2ML)/GaSb(8ML)}×30 were grown,respectly.Period thickness, defect density, the vertical strain were analyzed by X-ray double crystal symmetry diffraction. Data show that when the InSb layer is 1.0ML, we got the best quality of the material structure. And 3 #'s quality is better than 1#, indicating InSb layer has a great affect on the structure quality of short-period sample. The non-symmetric double crystal X-ray diffraction analysis shows that the InSb layer in 0.2ML 1.0ML range has little effect on vertical strain, but has great effect on parallel strain.Atomic force microscope (AFM) testing, shows that the degree of roughness of sample 1#, sample 2# and sample 3# are respectly as 2.215nm,1.230nm and 1.216nm.It also shows that the thickness of like-InSb layer has greater affect on the short period superlattice's surface quality than that of large period superlattice.Infrared absorption and photoluminescence properties of superlattice analysis by PL spectra and FTIR spectra testing. Infrared absorption peaks ascribe to the transition absorption between E_c1-E_HH1,E_c1-E_LH1,E_c1-E_HH2 energy level . PL peak ascribe to electron - hole recombination of the Ec1-EHH1 energy level. Short period superlattice has Light emission but The long-period superlattice is not observed significant luminescence, indicate that reduced period thickness is propitious to restrain Auger recombination, and then propitious to increase luminescence.By HALL test, we found that ,2#'s Hall mobility (70k,21003cm2/v·s) is much higher than the other sample's . We think that there is like-InSb band structure in the superlattice interface, which induce the electron mobility substantially increased, hole mobility decreased, resulting in Hall mobility substantial increase .With the analysis,we conclude that Interface structure has a great affect on superlattice structure,surface morphology,optical properties and electrical properties. It is indicated that the quality and performance of material can be improved by adjusting the growth process in the superlattice interface, controling interface to adjust the superlattice structure in the dependent variable.