Spectroscopic investigations of donor and acceptor states in n- and p-doped ZnTe epilayers

Abstract

ZnTe epilayers were grown on (001) GaAs and (001) GaSb substrates by metalorganic vapour phase epitaxy (MOVPE) and hot wall epitaxy (HWE). An extensive study of near gap photoluminescence (PL) has been made using selective-pair luminescence (SPL), two-electron transitions (TETs) and two-hole transitions (THTs). As grown and intentionally doped layers have been used. Excited donor states were investigated in I-doped ZnTe/GaAs layers. The magnetic field splitting of p-states leads to an effective conduction band mass of m ∗ e = 0.117m 0 . The hydrogenic model implies a static dielectric constant ϵ st = 9.4. A small biaxial strain splits the excitonic transitions. We obtained the Luttinger parameter γ 1 = 3.8 from the free exciton 1s and 2s levels. The excited states of an As acceptor were investigated by resonant excitation of free standing As-doped ZnTe layers and the Luttinger parameters γ 2 = 0.72 and γ 3 = 1.3 were derived. Magnetic field splitting yields the parameters κ A = −0.27 and q A = −0.015.