Epitaxial layers about 1 mu m thick of GaAs, InP, CdTe, EuS or SrS on
Si or GaAs substrates exhibit a strain -10(-3) < epsilon(0) < 10(-3) a
t the temperature of deposition. The strain remains on cooling until a
critical temperature T-c reached. The layers adhere to the substrates
below T-c and adopt different strains epsilon'' and epsilon(perpendic
ular to) parallel and perpendicular respectively to the substrate. The
T-c and epsilon(0) values often vary on annealing above 160-400 degre
es C. The ratio -(epsilon(perpendicular to) -epsilon(0))/(epsilon'' -e
psilon(0)) remains independent of temperature and annealing. Stable ep
itaxial layers with constant epsilon(0) and T-c values can be obtained
in some cases by deposition on buffer layers or stepped substrates.