Electrical properties of bulk, non-polar, semi-insulating M-GaN grown by the ammonothermal method

Bulk, non-polar M-GaN grown by the Ammonothermal method was studied using dark current versus temperature measurements, photocurrent spectra, photoinduced current transient spectroscopy (PICTS), high temperature current-voltage (I-V), and low-frequency capacitance-voltage (C-V). These measurements show the samples are semi-insulating p-type, with the Fermi level pinned near Ev + 0.9 eV. The concentration of uncompensated acceptors pinning the Fermi level is low, ∼1014 cm-3, while the deep trap spectra are dominated by hole traps with ionization energies close to 0.7 eV, 0.9 eV, and 1.2 eV. The former determine the temperature dependence of photocurrent, while the 0.9 eV defects are the ones pinning the Fermi level. The excellent structural properties and high photosensitivity of the non-polar ammono-grown GaN indicate they may have applications as for radiation detectors and as substrates for nonpolar AlGaN/GaN enhancement mode high electron mobility transistors.