Lattice parameters of bulk GaN fabricated by halide vapor phase epitaxy

The lattice parameters of low-defect density undoped bulk GaN fabricated by halide vapor phase epitaxy (HVPE) and removal of the substrate are precisely determined using high-resolution X-ray diffraction. The obtained values, c=5.18523A˚ and a=3.18926A˚ are compared with the lattice parameters of free-standing HVPE-GaN from different sources and found to be representative for state-of-the-art undoped HVPE bulk GaN material. A comparison with bulk GaN fabricated by the high pressure technique and homoepitaxial GaN layer is made, and the observed differences are discussed in terms of their free-electron concentrations, point and structural defects.