A study was made of dislocation etch pit density profiles in CdHgTe (100) layers which had been grown onto GaAs (100) by means of metalorganic chemical vapor deposition. The dislocation profiles differed in CdHgTe (111)B and CdHgTe(100) layers. Thus, misfit dislocations in the CdHgTe (111)B layers were concentrated near to the CdHgTe/CdTe interfaces. This was because of slip planes which were parallel to the interfaces. Away from the CdHgTe/CdTe interface, the CdHgTe (111)B dislocation density remained almost constant. In the case of CdHgTe (100) layers, the dislocations propagated monotonically to the surface and the dislocation density decreased gradually as dislocations were incorporated with increasing CdHgTe (100) layer thickness. The dislocation reduction was small in CdHgTe (100) layers which were more than 10 from the CdHgTe/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 CdHgTe (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