Abstract
Gamma-ray irradiations of up to 500 kGy on homoepitaxial n-type GaN layers were carried out, and the formation of electron traps was investigated by deep-level transient spectroscopy (DLTS) using Ni Schottky barrier diodes (SBDs). Before performing DLTS, current–voltage (I–V) and capacitance–voltage (C–V) measurements of the SBDs were performed and it was found that there was no change in the net donor concentration, ideality factor, and Schottky barrier height after irradiation. In the DLTS measurements, two new peaks, labeled G1 and G2, were observed after irradiation. The filling pulse width dependence of G1 revealed that the peak consists of two electron trap levels, labeled G1a (EC − 0.13 eV) and G1b (EC − 0.14 eV). Isothermal capacitance transient spectroscopy measurements of samples with different Schottky barrier heights showed that the G2 peak is a complex peak consisting of at least three electron traps, labeled G2a (EC − 0.80 eV), G2b (EC − 0.98 eV), and G2c (EC − 1.08 eV). The production rates (formation rates of traps by gamma-ray irradiation) for each trap were obtained. Finally, we investigated the annealing behavior of each trap and found that G1b and G2b decreased by the same amount with increasing annealing temperature, suggesting that the behavior originates from a recombination of vacancy–interstitial (Frenkel) pairs.
Highlights
Radiation-resistant electron devices are expected to find use in space satellites, particle accelerators, and nuclear reactors
We studied electron trap levels formed by gamma-ray irradiation on homoepitaxial n-type gallium nitride (GaN) by deep-level transient spectroscopy (DLTS)
We concluded that our results showed an original effect by gamma-ray irradiation due to a low threading dislocation density (TDD) and found that gamma-rays of 200 kGy did not affect the Schottky barrier diodes (SBDs) characteristics
Summary
Radiation-resistant electron devices are expected to find use in space satellites, particle accelerators, and nuclear reactors. Shmidt et al irradiated gamma-rays on metalorganic vapor phase epitaxy (MOVPE)-grown n-type GaN on sapphire and performed deep-level transient spectroscopy (DLTS).. Shmidt et al irradiated gamma-rays on metalorganic vapor phase epitaxy (MOVPE)-grown n-type GaN on sapphire and performed deep-level transient spectroscopy (DLTS).20 They found that the trap concentration of E2 (EC − 0.59 eV) observed in the asgrown samples increased by irradiation and two new electron traps were formed, E4 (EC − 0.155 eV) and E5 (EC − 0.95 eV). UmanaMembreno et al. irradiated gamma-rays on MOVPE-grown n-type GaN on sapphire They performed DLTS in the temperature range of 60–300 K to investigate in detail the trap equivalent of E4 observed by Shmidt et al They found that E4 consists of three electron traps G1 (EC − 0.088 eV), G2 (EC − 0.104 eV), and G3 (EC − 0.144 eV). We considered that this behavior originates from the recombination of nitrogen vacancies and nitrogen interstitials
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