TY - JOUR
TI - Lattice mismatch and conductivity in LTAlGaAs layers
AU - Lagadas, M.
AU - Calamiotou, M.
AU - Androulidaki, M.
AU - Hatzopoulos, Z.
AU - Christou, A.
JO - Microelectronic Engineering
PY - 1998
VL - 43-44
TODO - null
SP - 575-580
PB - Elsevier
SN - 0167-9317
TODO - 10.1016/S0167-9317(98)00229-9
TODO - null
TODO - The lattice mismatch of as-grown and annealed Low Temperature (LT) AlxGa1-xAs layers, epitaxially grown by Molecular Beam Epitaxy on (001) S.I. GaAs substrates, has been investigated as a function of growth conditions. The variation of electrical conduction in the temperature range of 150 K to 400 K has also been examined. The relaxed lattice mismatch due to the LT growth increases as the growth temperature decreases and as the V/III equivalent pressure ratio increases. For the same growth conditions the relaxed lattice expansion is higher in the LT GaAs than in the LT AlxGa1-xAs layers. The lattice expansion in LT AlxGa1-xAs decreases by increasing the Al concentration. The conductivity measurements have revealed the presence of hopping conduction in LT AlxGa1-xAs layers (T < 300 K) with a characteristic activation energy Eo increasing from 31 meV to 46 meV as the Al concentration rises from 0.19 to 0.65. The rise in Eo is caused by the high density of acceptor states. These acceptor states can be attributed to gallium vacancies as in the case of LTGaAs layers. The increase in gallium vacancy concentration is consistent with the lower dilation of the lattice constant in the LTAlxGa1-xAs layers compared with that of LTGaAs. © 1998 Elsevier Science B.V. All rights reserved.
ER -