Formation of high-quality bulk-like GaN layers is of great importance since they are used as substrates for further epitaxy of light emitting structures and can facilitate efficient light extraction from light emitting diodes. The best-quality GaN epilayers are obtained by using homoepitaxial growth over bulk GaN crystals. However at present, the size and growth rate of the high-pressure crystals are limited. Hydride vapor phase epitaxy (HVPE) offers large growth rates with relatively good quality of crystals. Optical properties under high excitation conditions, which are important for establishment of laser and high-power LED operation regime, are not well investigated in HVPE grown GaN.
We have studied carrier recombination dynamics in HVPE grown GaN at room temperature by means of transient photoluminescence under high photoexcitation conditions that are close to stimulated emission regime. The obtained luminescence transient was shown to be in a good agreement with a model of saturated centers of nonradiative recombination with the trap density of ~ 1017 cm-3 and carrier recombination coefficients of ~ 10-8 cm3/s. In such a regime, the lifetimes of electrons and holes have a common value of 410 ps. This value is smaller than that measured in homoepitaxialy grown samples but it is considerably higher than in high quality MOCVD grown epilayers on sapphire. This suggests high potential of HVPE grown GaN for short-wavelength optoelectronics applications.

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1. Carrier recombination under one-photon and two-photon excitation in GaN epilayers
2. Recognition of chemical (electrically active) non-homogeneities in thick HVPE-grown GaN layers
3. Influence of n-type doping on light emission properties of GaN layers and GaN-based quantum well structures
4. Application of picosecond four-wave mixing and photoluminescence techniques for investigation of carrier dynamics in bulk crystals and heterostructures of GaN
5. Monte Carlo simulation approach for a quantitative characterization of the band edge in InGaN quantum wells
6. Solid-state lighting
7. Stimulated emission in InGaN/GaN structures with different quantum well width
8. Simulation of localized exciton hopping in quaternary AlInGaN
9. Impact of post-growt thermal annealing on emission of InGaN/GaN multiple quantum wells