Trap states in n‐GaN grown on AlN/sapphire template by MOVPE

Abstract

Using epitaxial AlN/sapphire templates, high crystalline quality GaN films are grown on them by metal organic chemical vapour deposition. The electron traps behaviour of these GaN films were observed by deep level transient spectroscopy (DLTS). Four distinct trap levels were ob‐served in both n‐GaN grown on AlN/sapphire template and on conventional low temperature buffer layer (LT‐BL)/sapphire. The magnitude the of the DLTS signal E1 and E2 were almost same. It suggests that E1 is not only associate with dislocation density but also other defect. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Radiation-induced defects in GaN bulk grown by halide vapor phase epitaxy

“…2(a)) and annealed out at $1000 C with the trap concentration being unaffected by irradiation. It has previously been observed by Ito et al 23 but no defect model has been suggested for this trap. Since the concentration is unaffected by electron irradiation, the level is unlikely to be associated with a primary intrinsic defect.…”

Investigation of deep levels in bulk GaN material grown by halide vapor phase epitaxy

“…26) that are strongly bonded along threading dislocation core site. However, in studies by Ito et al 11 on GaN layers grown on AlN and sapphire it has been observed that the concentration of E1 does not depend on the TDD. Additionally, it has been suggested by Fang et al One of the stronger peaks in the spectra is E2.…”

“…There have been many previous studies of deep levels in GaN grown by various techniques, and, so far, most of the defect levels have been found when carrying out DLTS measurement in the temperature range of 80 K-500 K. [5][6][7][8][9][10] There have been reports on measurements at higher temperatures, [11][12][13][14][15] and among these the highest temperature at which DLTS peaks have been reported is about 620 K. 15 However, since energy levels of efficient recombination centers are situated in the middle of the band gap, and GaN is a wide-band-gap material, DLTS scans at higher temperatures are necessary. Despite that a large number of DLTS investigations have been reported in the temperature range 80 K-500 K, the identities of most of the observed peaks are still speculative.…”

Localized deep levels in Al x Ga 1− x N epitaxial films with various Al compositions

“…The energy position was referred to the maximum of the valence band. Figure 6 also includes the DLTS data of dominant deep levels reported for GaN, [25][26][27] Al 0.12 Ga 0.88 N, [28] and Al 0.17 Ga 0.83 N. [29] For AlN, we plotted the deep-level emission energies in CL spectra. [30] To plot the conduction band edge E c , reported band data, which were determined by optical observation, [31] cathodoluminescence [32] and photoreflectance measurements at room temperature, [33] were used as a function of the Al composition.…”