Realization of High‐Resistive Ni‐Doped GaN Crystal by Hydride Vapor‐Phase Epitaxy

Herein, high‐resistivity GaN is studied for use as an epitaxial substrate in lateral power devices. Fe‐, C‐, Mn‐, and Zn‐doped GaN monocrystals have high resistivity at a doping concentration of ≈1 × 10 18 cm −3 . However, a low doping concentration is preferred for growing GaN monocrystals; therefore, other dopants for GaN that yield high resistivity at a doping concentration less than 1 × 10 18 cm −3 must be identified. Herein, NiCl 2 is used as a precursor to grow Ni‐doped GaN monocrystals on GaN substrates via hydride vapor‐phase epitaxy. Two Ni‐doped GaN substrates with Ni concentrations corresponding to 2.7 × 10 17 and 2.9 × 10 18 cm −3 are obtained by varying the partial pressure of NiCl 2 . The resistivity of Ni‐doped GaN monocrystals is measured as a function of temperature using Hall effect measurements. The GaN monocrystals doped with 2.7 × 10 17 cm −3 of Ni have a higher resistivity than those doped with 2.9 × 10 18 cm −3 of Ni at 600–900 K. Charge‐neutrality calculations have shown that the depth of the Ni acceptor level in GaN is 1.4–1.5 eV, indicating that Ni‐doped GaN monocrystals have high resistivity owing to the deep acceptor level of Ni.