Growth and structural characterization of intrinsic, acceptor, and donor doped (Mg,Zn)O epilayers via metalorganic vapor phase epitaxy on (1 0 1¯ 0) ZnO substrates

Abstract

We report on the epitaxial growth of ZnO and Mg x Zn 1− x O films grown epitaxially on (1 0 1¯ 0) ZnO substrates for 0≤ x≤0.50 via a metal organic vapor phase epitaxy (MOVPE) process. Morphological properties of these epilayers investigated using scanning electron microscopy (SEM) and atomic force microscopy (AFM) indicate step-flow growth mode. Structural analysis conducted by high resolution X-ray diffraction (HRXRD) and transmission electron microscopy (TEM) indicates monocrystalline deposition and increasing biaxial strain with increase in Mg concentration. In particular, TEM indicates the prevalence of stacking faults as the main strain defects in Mg x Zn 1− x O epilayers. Temperature-dependent photoluminescence studies identify neutral donor–acceptor pair transitions occurring in Mg 0.20Zn 0.80O at 3.45 eV corresponding to an acceptor energy of 211 meV. Acceptor profiles measured by secondary ion mass spectrometry (SIMS) reveal the presence of dopant diffusion.