Dislocation Profiles in HgCdTe(100) on GaAs(100) Grown by Metalorganic Chemical Vapor Deposition

摘要

We studied dislocation etch pit density (EPD) profiles in HgCdTe(100) layers grown on GaAs(100) by metalorganic chemical vapor deposition. Dislocation profiles in HgCdTe(111)B and HgCdTe(100) layers differ as follows: Misfit dislocations in HgCdTe(111)B layers are concentrated near the HgCdTe/CdTe interfaces because of slip planes parallel to the interfaces. Away from the HgCdTe/CdTe interface, the HgCdTe(111)B dislocation density remains almost constant. In HgCdTe(100) layers, however, the dislocations propagate monotonically to the surface and the dislocation density decreases gradually as dislocations are incorporated with increasing HgCdTe(100) layer thicknesses. The dislocation reduction was small in HgCdTe(100) layers more than 10 μm from the HgCdTe/CdTe interface. The CdTe(100) buffer thickness and dislocation density were similarly related. Since dislocations glide to accommodate the lattice distortion and this movement increases the probability of dislocation incorporation, incorporation proceeds in limited regions from each interface where the lattice distortion and strain are sufficient. We obtained the minimum EPD in HgCdTe(100) of 1 to 3 x 10~6 cm~(-2) by growing both the epitaxial layers more than 8 μm thick.