The formation of intrinsic point defects in the N-sublattice of semi-insulating Mg-doped GaN crystals grown by the ammonothermal method (SI AT-GaN:Mg) was investigated for the first time. The grown-in defects produced by the displacement of nitrogen atoms were experimentally observed as deep traps revealed by the Laplace transform photoinduced transient spectroscopy in the compensated p-type GaN:Mg crystals with the Mg concentrations of 6 × 1018 and 2 × 1019 cm−3 and resistivities of ~1011 Ωcm and ~106 Ωcm, respectively. In both kinds of materials, three closely located traps with activation energies of 430, 450, and 460 meV were revealed. The traps, whose concentrations in the stronger-doped material were found to be significantly higher, are assigned to the (3+/+) and (2+/+) transition levels of nitrogen vacancies as well as to the (2+/+) level of nitrogen split interstitials, respectively. In the material with the lower Mg concentration, a middle-gap trap with the activation energy of 1870 meV was found to be predominant. The results are confirmed and quantitatively described by temperature-dependent Hall effect measurements. The mechanism of nitrogen atom displacement due to the local strain field arising in SI AT GaN:Mg is proposed and the effect of the Mg concentration on the charge compensation is discussed.
The data that support those findings contain:
1 SIMS results of the studied GaN:Mg crystals.
2.Reciprocal of dark current vs inverse temperature.
3.Mobility-lifetime product vs temperature.
4.Inverse Laplace Amplitude derived from the photocurrent relaxation waveforms recorded at Laplace Photo-Induced Transient Spectroscopy vs emission rate (one dimensional Laplace spectra reavealing T1-T4 traps).
5. Thermal emission rate of charge carriers (measured by Laplace Photo-Induced Transient Spectroscopy) vs inverse temperature (Arhenius plots).
6.Hall effect data vs temperature - resistivity, hole concentration and mobility derived from Van der Pauw voltages measured at different configurations of contacts and Hall voltages measured vs magnetic field at specific temperatures.
7.Matlab source code used for the solution of charge neutrality equation.
(2024-02)
