A study was made of dislocation etch pit density profiles in HgCdTe (100) layers which had been grown onto GaAs (100) by means of metalorganic chemical vapor deposition. The dislocation profiles differed in HgCdTe (111)B and HgCdTe(100) layers. Thus, misfit dislocations in the HgCdTe (111)B layers were concentrated near to the HgCdTe/CdTe interfaces. This was because of slip planes which were parallel to the interfaces. Away from the HgCdTe/CdTe interface, the HgCdTe (111)B dislocation density remained almost constant. In the case of HgCdTe (100) layers, the dislocations propagated monotonically to the surface and the dislocation density decreased gradually as dislocations were incorporated with increasing HgCdTe (100) layer thickness. The dislocation reduction was small in HgCdTe (100) layers which were more than 10 from the HgCdTe/CdTe interface. The CdTe (100) buffer thickness and dislocation density were similarly related. Because dislocations glided so as to accommodate the lattice distortion, and because this movement increased the probability of dislocation incorporation, the latter proceeded within limited distances from each interface where the lattice distortion and strain were sufficient. A minimum etch pit density of 106 to 3 x 106/cm2, in HgCdTe (100), was obtained by growing both epitaxial layers to a thickness of more than 8.

H.Nishino, S.Murakami, T.Saito, Y.Nishijima, H.Takigawa: Journal of Electronic Materials, 1995, 24[5], 533-7