Electrical and optical properties of GaN films implanted with Mn and Co

Abstract

Optical transmission spectra, microcathodoluminescence spectra, capacitance–voltage and capacitance–frequency curves, temperature dependence of resistivity and deep level spectra with both electrical and optical injection were measured on n-GaN samples implanted with high doses of Mn (3×1016 and 4×1016 cm−2) and Co (4×1016 cm−2). From optical transmission it was found that Mn forms a deep acceptor near Ev+1.8 eV while the Co acceptor is about 0.1 eV deeper. In addition, Mn and Co form complexes with native defects and these complexes are deep electron traps with a level near Ec−0.5 eV. Such complexes are most likely responsible for a strong blue luminescence band with energy near 2.9 eV. Adjacent to the implanted region a defect region about 1 μm deep is formed, most likely by out-diffusion of point defects from the implanted zone during the 700 °C annealing used to partially remove the radiation damage. This region is characterized by a high density of electron traps at Ec−0.25 eV and Ec−0.7 eV and hole traps at Ev+0.2 eV, Ev+0.35 eV and Ev+0.45 eV.