InAs/GaInSb Superlattice Epitaxl Growth Simulation And Micro-Structure Research

The Kinetic Monte Carlo (KMC) method based on Solid-on-Solid (SOS) model has been used to simulate the growth of InAs/Ga_1-xIn_xSb superlattice (SL) grown by Molecular Beam Epitaxy (MBE). The band structure of InAs/Ga_1-x. In_xSb superlattice has been calculated by the Envelope Function method. On the basis of simulation and calculation, a SL photovoltaic deVice was designed.The simulation shows that, when the substrate temperature is 663K, the Roughness-Time curve of InAs/Ga_1-xIn_xSb growth on GaSb buffer displays a periodical oscillation, which agrees with the reported RHEED's patterns. It indicates the high quality SLs growth by MBE at this temperature. The InSb-like interface in the InAs/Ga_1-xIn_xSb SL is smoother than the GaAs-like version. Furthermore, the quality of film degrades as the In content increasing in the Ga_1-x In_xSb growth.In general, the SL period and In content contribute the band structure change of InAs/Ga_1-xIn_xSb SL. The caulation result exhibits that, the energy of SL HH1 subband rises and C1 declines when InAs layer thickness increases, so band gap E_g decreases; on the other hand, increasing the thickness of GalnSb layer results in both C1 and HH1 rise then E_g has little changes. Because the In content affects on both strain and most band structure parameters of GalnSb, the SL band structure will vary significantly due to the changing content. Besides, the energy of C1 subband declines and HH1 rises with In content increasing, which results in the quick decrease of band gap.A p-i-n photodiode based on InAs/Ga_0.9In_0.1Sb (3nm/2.7nm) superlattice has been designed. The active layer consists of 20 periods unintentional doped SLs sandwiched between 40 periods p-type SLs (GalnSb: Be 1×10¹⁷cm^-3) and 40 periods n-type SLs (InAs: Si 5×10¹⁷cm^-3). The dark current at 77K mainly make up of the generation-recombination (G-R) current and band-to-band tunneling current. The G-R current dominates the dark current when the re Verse bias lower than 16.5mV, while beyond 16.5mV the band-to-band tunneling current exceeds.