Optical characterization of ZnTe epilayers

Abstract

ZnTe epilayers were grown on (001) GaAs substrates by metalorganic vapour phase epitaxy (MOVPE) and hot wall epitaxy (HWE). The near band luminscence was extensively studied by resonant excitation methods. Investigations of excited donor states in I-doped ZnTe layers yield the effective electron mass m e * =0.117 m 0 and the static dielectric constant ɛ st=9.4. The Luttinger parameter γ 1=3.8 was obtained from the free exciton 1s and 2s levels. Shallow acceptor states were observed in free standing As- and P-doped ZnTe layers and the Luttinger parameters γ 2=0.72 and γ 3=1.3 were derived. The magnetic field splitting of the 1S 3/2 acceptor ground state yields the parameters κ A=−0.27 and q A=−0.015. The temperature shift and broadening of the n=1 exciton peak are deduced from absorption measurements. The proper theories are presented which include excitonic effects, indirect transitions and surface roughness.