Neutron irradiation effect on radio-frequency magnetron-sputtered GaN thin films and Au/GaN Schottky diodes

Abstract

Effects of gamma-ray irradiation on the microstructural and luminescent properties of radio-frequency magnetron-sputtered GaN thin filmsThe microstructural and luminescent properties of pre-irradiated and neutron-irradiated sputtered GaN thin films were systematically investigated. Analytical results revealed that the optimal (1 ϫ10 13 n/cm 2 ) neutron irradiation fluence could not only promote the crystallinity of GaN thin films, but also effectively repress the occurrence of deep level luminescence in the photoluminescence spectrum due to the creation of nitrogen-related deep electron traps (E t1 ). Moreover, from both the Fourier transform infrared spectroscopy and yellow band emission results, it is strongly suggested that Ga-H complexes in the vicinity of the nitrogen vacancy, forming the E t2 trap, possibly act as the origin of yellow band emission in GaN material. The superior I -V characteristics resulting from the optimal (1ϫ10 13 n/cm 2 ) neutron irradiation fluence on the Au/sputtered GaN Schottky diode were attributed mainly to the superior crystallinity, creating the fewer deep electron traps of E t1 , leading to a smaller turn-on voltage as well as a larger conduction current in the forward-biased situation. In the reverse-biased condition, the smaller leakage current and the larger breakdown voltage were suggested to probably be due to the presence of fewer nitrogen vacancies and/or less Ga-Au compound formation at the Au/GaN junction.

Neutron irradiation effects in AlGaN/GaN heterojunctions

“…The authors are aware of only one paper in which the electrical characteristics of nGaN films prepared by magnetron sputtering were investigated before and after neutron irradiation (see Ref. [9], where it was shown that the electrical properties of such epilayers started to decrease after exposure to doses higher than 10 14 cm À2 ). In what follows, we discuss the effects of neutron irradiation on electrical properties of AlGaN/GaN structures grown by metalorganic chemical vapor deposition (MOCVD).…”

Highly oriented GaN films grown on ZnO buffer layer over quartz substrates by reactive sputtering of GaAs target

“…There have been several early reports on the growth of GaN films by reactive sputtering of Ga target with nitrogen or nitrogen-argon mixture [35][36][37], though problems of reproducibility arising out of the low melting temperature of gallium have been reported [38]. However, during the last few years, GaN films have been deposited using both Ga [18][19][20][21][22] or GaN [23][24][25][26][27][28] targets. The growth of GaN films has also been reported [29,39] by reactive sputtering of a GaAs target with 100% nitrogen.…”

Spectroscopic ellipsometry studies of GaN films deposited by reactive rf sputtering of GaAs target

“…1,8 However, owing to their enormous application potential, there has recently been increasing interest in polycrystalline GaN films grown by MBE, [9][10][11][12][13][14] MOCVD, [15][16][17][18] and sputtering. [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] Polycrystalline, 19 nanocrystalline, 20 and amorphous 37 GaN have also shown good luminescence characteristics. Applications of polycrystalline GaN films have been demonstrated in LEDs, 38,39 white lighting, 39 UV photodetectors, 40 solar cells, 41,42 thin film transistors, 43,44 and field electron emitters, 16,45 and suitability of GaN films for application in large area flat panel displays has also been explored.…”

“…There have been several early reports on the growth of GaN films by reactive sputtering of Ga target with nitrogen or nitrogenargon mixture, [21][22][23] though problems of reproducibility arising out of the low melting temperature of gallium have been reported. 24 During the past few years, polycrystalline GaN films have been deposited by sputtering using Ga, [25][26][27][28] GaN, [29][30][31][32][33][34] or GaAs ͑Ref. 35͒ targets.…”