Molecular Beam Epitaxy Growth Of GaAs Based InSb And InAsSb Thin Film

Currently,detectors working in mid-wave?3⁵?m?have a wide range of applications.In the field of fast response photonic detectors,HgCdTe?mercury cadmium teluride?devices of II-VI group has made many important achievements,and still occupies the leading position.However,due to HgCdTe crystal still has some shortcomings,such as poor structural integrity and uneven aloy composition,which affect the quality of thermal imaging and hinder the improvement of detector working temperature.Therefore,the research of InSb and InAsSb and other new mid-wave infrared photon detector materials has been widely concerned.In this paper,we use molecular beam epitaxy equipment to epitaxial high-quality InSb and InAsSb materials on GaAs substrate.In order to obtain high quality epitaxial materials,we focus on different buffer structures and growth methods.The main conclusions are as follows:The epitaxy properties of GaAs-based GaSb thin films were investigated under different growth conditions,the results showed notable reduction in threading dislocation densities?TDDs?and hillocks densities?HDs?of GaSb buffer layer when the temperature of substrates rising to Tc?surface reconstruction conversion temperature?+110?and growth rate decreasing to 0.25 mono layer per second?ML/s?.These conditions led to gradual changes in GaSb epilayer surface morphologies from tiny hilocks to near-parallel steps.The AlInSb/GaSb compound buffers were studied by employing five different structures of AlInSb metamorphic buffer layers grown on optimized GaSb layers,and then characterized by various analytical methods.The effect of buffer layer on defects and the mechanism of restraining defects are studied.It was shown that the buffer layer with low-temperature interface layer and superlattice structure presents obvious inhibitory effects on defects.Among these,specimens with superlattice interface exhibits the lowest TDDs of 3.1×10⁷ cm^-2 and moderate HDs of 2.4×10⁷ cm^-2.High quality InSb device structure can be epitaxed on the optimized AlInSb strain buffer layer.A series of InAsSb thin films were grown on GaAs substrates with GaSb buffer layer by MBE,the effect of nucleation layer grown under different conditions on the quality of InAsSb thin films was studied,and the mechanism of the inhibition defect propagation by AlSb/GaSb superlattice in heteroepitaxy was explored.In the process of component control,by optimizing the growth mode,the repeatability of component control of epitaxial materials is improved,and the Sb component at the GaSb/InAsSb interface is controlled,so as to released the increase of strain at the interface caused by too large Sb component.It can be used to control the composition of InAsSb materials.The low temperature AlAsSb smooth layer is used to suppress the defects in InAsSb contact layer caused by temperature change.On this basis,InAsSb nbn device structure is fabricated.