DEPENDENCE OF DEFECT STRUCTURE OF SEMICONDUCTOR THIN LAYERS ON PRESSURE ANNEALLING
J.Bak-Misiuk1, J.Adamczewska1, J.Domagala1, Z.R. Zytkiewicz1, A.Misiuk2, H.B.Surma2
1Institute of Physics, Polish Academy of
Sciences, Al.Lotników 32/46, 02-668 Warsaw; 2Institute
of Electron Technology, Al.Lotników 32/46, 02-668 Warsaw,Poland
The material response on stress at high temperature is of fundamental interest. Therefore such measurements are carried out very extensively. However, most reports concern silicon single crystals and only few of other semiconductors.
In this report we present investigations of anisotropic relaxation in AlGaAs/GaAs layers of (001) orientation after high pressure - high temperature (HP-HT) treatment. Investigated layers of 3-13 m thickness were grown by MBE and LPE methods. Characterization of samples was performed using X-ray high - resolution diffractometer in double and triple axis configuration with the sample aligned with either [110] or [-110] direction perpendicular to the diffraction plane.
Observed changes in the lattice parameter and defect structure
of the layers after treatment were related to the strain
relaxation and could be explained as an effect of creation of
misfit dislocations and of other extended defects. Our results
indicated also that in the AlGaAs/GaAs system the relaxation of
layers was related to initial strain relaxation degree (before
treatment) and showed directional character after the HP-HT
treatment. This effect can be explained by higher mobility of the
[-110] oriented dislocations in comparison to these oriented in
the [110] direction. This effect leads to different dislocation
density in the both mentioned directions and explains the
observed anisotropy of lattice misfit relaxation. Our results are
in agreement with those reported by Tanner et al. for AlAs/GaAs
layers [1].
1. B.K.Tanner, A.G.Turnbull, C.R.Stanley, A.H.Kean and M.McElhinney, Appl. Phys. Lett. 59, 2272 (1991).
This work was supported in part by the Polish State Commitee
of Scientific Research (KBN) grant 2P03B 021 09/113/P03/95/09.