Annealing effects on electrical properties of MgZnO films grown by pulsed laser deposition

Abstract

Electrical properties and deep trap spectra are reported for MgZnO(P) films grown by pulsed laser deposition on undoped n-ZnO substrates. The as-grown films are n type with a “bulk” donor concentration of ∼1018cm−3 and have a compensated high resistivity layer near the surface. Deep trap spectra in these films are dominated by electron traps with an activation energy of 0.3eV, hole traps with an activation energy of 0.14eV, and some unidentified electron traps with a barrier for capture of electrons. After annealing in oxygen at 800°C the MgZnO(P) becomes p type, with the dominant hole traps having an activation energy of 0.2eV. The space charge region of the formed p-n junction is mainly located in the n-ZnO substrate. The main hole traps in this part of the heterojunction have activation energies of 0.14 and 0.84eV, while the main electron traps have activation energies of 0.15 and 0.3eV.