Researches On Microstructures At Lattice Mismatch System Of In_xGa_1-xAs/InP

InxGa1-xAs material is an important Ⅲ-Ⅴ Semiconductor Materials ranges in the1～3μm infrared wave bands. It can be formed by InAs and GaAs in any proportion,and its lattice constants show linear change with different contents. The latticeconstants can range from0.5653nm (GaAs) to0.6058nm (InAs), and thecorresponding spectrum response range from3.5μm to0.87μm. It is the ideal materialto prepare shortwave infrared detector. In InP substrate research field， when Incontents x is0.53, InxGa1-xAs epitaxial layer and InP substrate is lattice matching, andits spectrum response is1.7μm. If the spectrum response is extended to2.5μm, theInxGa1-xAs epitaxial layer will grow with large lattice mismatch on InP substrate.Because of this, heterostructures and misfit dislocation appear. The large latticemismatch results in a mass of dislocation in epitaxial layers, which affect its qualityseriously.A pretty good way to solve this problem is inserting a buffer layer betweenthe substrate and the epitaxial layers.In this paper, InxGa1-xAs/InP heterostructures was grown by metalorganicchemical vapor deposition (MOCVD) technique. And InxGa1-xAs epitaxial layers weregrown with different growth parameters. Using scanning electron microscope (SEM)and transmission electron microscopy (TEM) as research tools, by studying themicrostructure of the surface morphologies and interior microstructure, weinvestigated the influence of the growth parameters on surface morphologies and theinterface structure, explored the reason for dislocation defect formation, anddetermined the dislocation patterns.As the experimental results suggest: the lower the growth temperature, thesmoother the buffer layer and the lower the dislocation density of the buffer layer, andthe dislocation density of the interface is significantly higher than the epitaxial layer;when In contents of buffer layers are not more than0.82, the higher of indiumcontents, the higher quality of the surface of In0.82Ga0.28As; the thicker the buffer layeris, the lower dislocation density of the In0.82Ga0.28As epitaxial layer.By analyzing the STEM imagine and the simulated imagine of dislocation, we know that thedislocation of InxGa1xAs/InP(100)(x=0.82) heterostructure is caused by mismatchstrain and its motion. Using high resolution TEM images, we find that the dislocationin heterostructure majority is60°edge dislocation, but having a few is Lomerdislocation, and also exist stacking fault.