Defect reduction in GaN epilayers grown by metal-organic chemical vapor deposition with in situ SiNx nanonetwork

Abstract

Line and point defect reductions in thin GaN epilayers with single and double in situ SiN x nanonetworks on sapphire substrates grown by metal-organic chemical vapor deposition were studied by deep-level transient spectroscopy ͑DLTS͒, augmented by x-ray diffraction ͑XRD͒, and low temperature photoluminescence ͑PL͒. All samples measured by DLTS in the temperature range from 80 to 400 K exhibited trap A ͑peak at ϳ325 K͒ with an activation energy of 0.55-0.58 eV, and trap B ͑peak at ϳ155 K͒ with an activation energy of 0.21-0.28 eV. The concentrations of both traps were much lower for layers with SiN x nanonetwork compared to the reference sample. The lowest concentration was achieved for the sample with 6 min deposition SiN x nanonetwork, which was also lower than that for a sample prepared by conventional epitaxial lateral overgrowth. In concert with the DLTS results, PL and XRD linewidths were reduced for the samples with SiN x network indicating improved material quality. Consistent trend among optical, structural, and DLTS results suggests that SiN x network can effectively reduce both point and line defects.

Threading dislocation annihilation in the GaN layer on cone patterned sapphire substrate

“…3(b), indicating a TD density of 4.7 Â 10 7 cm À2 . The result is comparable with the result of traditional ELOG [14,15]. The decreasing of the TDs related EPD indicates the effect of the PSS to the improvement of crystalline quality.…”

Electrical and Optical Characterization of AlGaN/GaN HEMTs with In Situ and Ex Situ Deposited SiN x Layers

“…Their x-ray diffraction (XRD) characterization showed that in situ SiN x capping prevented the AlGaN layer from relaxing by forming TDs, which have been known to act as recombination centers in GaN. 23 Sample C exhibited the highest near-band-edge luminescence, a result also observed by Xie et al 24 Indeed, as some of the traps in the material would inevitably be near the surface, one could reasonably expect in situ SiN x to reduce the interface state density as well. The increased slope of the CV characteristics in Fig.…”

Status of Growth of Group III-Nitride Heterostructures for Deep Ultraviolet Light-Emitting Diodes

“…Therefore, dielectric mask material produced by ex situ deposition and etching procedures [77] or in situ spontaneous etching [78] can be used for ELO GaN and low Al-molar fraction AlGaN. Figure 6 shows a cross-sectional transmission electron microscopy (TEM) image of an ELO GaN sample on sapphire substrate with in-situ nanoporous SiNx mask [79].…”