Resonant excitation of intrinsic and shallow trap luminescence in MOVPE grown ZnTe layers

Abstract

We present high resolution spectra of excitons, shallow donors and acceptors in ZnTe epilayers grown on GaAs and GaSb by atmospheric pressure metal-organic vapor-phase epitaxy (MOVPE). Resonant excitation made the observation of selective-pair luminescence (SPL), two-electron transitions (TET) and two-hole transitions (THT) possible. The investigation of donor states in I-doped layers yields m ∗ e = 0.117 m 0 and a static dielectric constant ϵ st = 9.4. The Luttinger parameter γ 1 = 3.8 was obtained from 1s-and 2s-free exciton transitions. As-acceptor states were observed in strain-free layers. A fit to calculations of Baldareschi and Lipari leads to γ 2 = 0.72 and γ 3 = 1.3. Level shift and splitting in magnetic fields corroborated the present assignments. The magnetic parameters K A = -0.27 and q A = -0.015 were obtained from As-acceptor bound excitons and the first excited acceptor state.