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

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 (3×10 ¹⁶ and 4×10¹⁶cm^-2) and Co (4×10¹⁶cm^-2). From optical transmission it was found that Mn forms a deep acceptor near Ev+1.8eV 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-0.5eV. 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-0.25eV and Ec-0.7eV and hole traps at Ev+0.2eV, Ev+0.35eV and Ev+0.45eV.