U. Hilpert et al., Optical characterization of isolated Se(g)-type misfit dislocations and their influence on strain relief in thin ZnSe films, J PHYS-COND, 12(49), 2000, pp. 10169-10174
Microscopic information on the optical properties of Se(g)-type dislocation
s in ZnSe layers grown on (001) GaAs substrates by molecular beam epitaxy (
MBE) have been obtained by using micro-cathodo- and photoluminescence techn
iques. Se(g)-type misfit dislocations are found to nucleate first in high q
uality pseudomorphic Rims above the critical thickness, The individual Se(g
) misfit segments are evidenced as the only local emission centres of the s
o-called Y luminescence. The latter is found to be strongly polarized in th
e defect line direction and exhibits a pronounced spectrum fine structure,
which is related to the particular structural configuration, as determined
by the dissociation of perfect 60(-) dislocation segments into pairs of 30
degrees /90 degrees Shockley partials bordering a stacking fault ribbon.
Studying the dislocation induced Y luminescence with respect to polarizatio
n properties and correlation with defect structure yields essential argumen
ts supporting the idea that the dislocation-induced luminescence may be asc
ribed to ID excitonic states at the line defect.
The local strain field believed to be origin of defect bound electronic sta
tes could be examined at isolated Se(g) dislocations by analysing the micro
scopic dependence of observed polarization of the free exciton emission in
the layer matrix. The polarization properties of free exciton emission resu
lts from anisotropic relief of layer strain by the Se(g) misfit segment arr
angement.