Optical investigation of shallow acceptor states in GaN grown by hydride vapor-phase epitaxy

Abstract

The evolution of low-temperature photoluminescence ͑PL͒ spectra with the thickness of the layer ͑3-400 m͒ is investigated on high-quality GaN grown by hydride vapor-phase epitaxy. With increasing layer thickness, three acceptor bound exciton peaks are found to reduce in intensity, although the impurity concentrations, measured by secondary ion mass spectrometry, do not depend on the sample thickness. The observed acceptor transitions are attributed to intrinsic defects, originating from the substrate/layer interface and decreasing in density with the thickness of the layer. The optical properties, studied by reflectance, temperature and excitation power dependent PL, are compared to those of homoepitaxial GaN films grown by metalorganic chemical vapor deposition.

Recombination mechanism of photoluminescence in InN epilayers

“…The localization energy of bound excitons also needs to be taken into account. In general, the values of the localization energy of bound excitons are several millielectron volts for InX compounds (XZP, As, and Sb), 6-12 meV for GaN, and 16 meV for AlN [24][25][26][27][28][29][30]. Therefore, the binding energy of bound excitons with respect to the free electron-hole pairs has a value of 20 meV at most.…”

Carrier gas and position effects on GaN growth in a horizontal HVPE reactor: An experimental and numerical study

“…A second characteristic of the spectra is the shifting of the position of the FXA peak. With increasing thickness this position shifts to lower energies (from 3.482 eV for 17 mm to 3.473 eV for 45 mm), indicating a release of strain with increasing thickness [23]. Spectra (b) and (c) are taken on samples with almost equal thickness (17 and 18 mm), grown in two different growth runs at the same position on the disk, and show the effect of carrier gas.…”

Strain-free bulk-like GaN grown by hydride-vapor-phase-epitaxy on two-step epitaxial lateral overgrown GaN template

“…Transitions e and f may originate from intrinsic defects rather than from impurities as pointed out by Kirilyuk et al for similar features. 31 However, PL investigations of intentionally doped HVPE-grown material revealed features, which correspond to transitions e and f ͑after appropriate strain consideration͒ and were hence assigned to Mg and Zn acceptors, respectively. 32 The fact that an acceptor bound exciton has been reported to be present close to the position of line e in the majority of the HVPE-grown GaN material so far, where Mg is known to be a common contaminant, supports the interpretation of line e as being Mg related.…”