Composition and temperature dependence of the optical properties of Zn(1-x) Cd(x)Se (0 < or = x < or = 0.34) below the fundamental bandgap.
The II-VI ternary semiconductor alloy system Zn(1-x) Cd(x) Se with 0 < or = x < or = 0.2 has important applications as the active material in blue-green light-emitting diodes and lasers. For the wavelength and temperature ranges over which these devices are designed to operate, a knowledge of the optical properties of the alloys is important. We report the results of spectroscopic ellipsometry measurements of the real part of the dielectric function epsilon1 for Zn-rich Zn(1-x) Cd(x) Se layers deposited epitaxially on (100) GaAs. We derive compact expressions that allow one to calculate accurate epsilon1 spectra from 1.5 eV, the low-energy limit of our ellipsometer, to E0-0.05 eV, where E0 is the fundamental bandgap energy, for any composition and temperature within the ranges 0 < or = x < or = 0.34 and 25 < or = T < 260 degrees C. Furthermore, we expect that the results can also be extrapolated to cover the substrate temperature range typically used for the growth of these films (250-300 degrees C). Hence the results presented here are also useful in future real-time spectroscopic ellipsometry studies of Zn(1-x) Cd(x) Se film growth.
Lee
J
J
Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Flack
F
F
Samarth
N
N
Collins
R W
RW