Optical and Structural Properties of Cr-Doped GaN Grown by HVPE Method

Single crystalline Cr-doped GaN films are successfully grown by hydride vapor phase epitaxy. The structure analysis indicates that the film is uniform without detectable Cr precipitates or clusters and the Cr atoms are substituted for Ga sites. The impurity modes in the range 510–530 cm⁻¹ are observed by the Raman spectra. The modes are assigned to the host lattice defects caused by substitutional Cr. The donor-acceptor emission is found to locate at E_c−0.20 eV by analyzing the photoluminescence spectrum obtained at different temperatures, and the emission is attributed to the structural defects caused by Cr_Ga−V_N complex. The superconductor quantum interference device results show that the Cr-doped GaN film without detectable Cr precipitates or clusters exhibits paramagnetic properties.