III-nitride semiconductors are successfully applied for blue and UV optoelectronic devices such as light emitting and laser diodes, as well as high-voltage and high-power electronic devices. Although these devices are commercially available, there are a lot of unsolved problems related to the high density of nonradiative traps in GaN epilayers. The conventional heteroepitaxial growth of GaN films results in high dislocation densities (10⁸ – 10¹⁰ cm^-2) which affect both optical and electrical device properties. One of the ways to reduce threading dislocations in the film is growth of the homoepitaxial layers of large thickness by hydride vapor phase epitaxy (HVPE).

In recent decade, significant progress has been achieved in growth of GaN layers, which has an impact on dominating luminescence decay processes. For the surface excited high quality GaN layers, due to efficient diffusion created carriers rapidly escapes from the excited region, thus luminescence lifetime cannot be treated as materials quality factor anymore. Recently, we proposed application of two-photon excitation conditions for luminescence characterization of high quality GaN.

Here we present time-resolved luminescence properties of ~100-μm thick GaN epilayers grown by HVPE over three different substrates excited under one-photon (1P) and two-photon (2P) conditions. The excited sample area is much bigger than carrier diffusion depth and we can neglect carrier diffusion processes. Experimental data was fitted with consideration to theoretical spatial-temporal distribution of the plasma density.

We show that the investigation of luminescence transients obtained for 1P and 2P excitations allows for the estimation of carrier lifetime, related to the density of nonradiative traps, and of the carrier bipolar diffusion coefficient. The impact of the equilibrium carrier density on the luminescence dynamics of highly excited GaN is discussed.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/11456 must be provided.

1. Homoepitaxial HVPE-GaN growth on non-polar and semi-polar seeds
2. Preparation of free-standing GaN substrates from thick GaN layers crystallized by Hydride Vapor Phase Epitaxy on ammonothermally grown GaN seeds
3. Homoepitaxial HVPE-GaN growth on non-polar and semi-polar seeds
4. Preparation of free-standing GaN substrates from thick GaN layers crystallized by Hydride Vapor Phase Epitaxy on ammonothermally grown GaN seeds
5. Role and influence of impurities on GaN crystal grown from liquid solution under high nitrogen pressure in multi-feed-seed configuration
6. Efficiency „droop” in nitride light emitters
7. Surface morphology of InGaN layers
8. Indium segregation in Al_1-xIn_xN investigated by photoluminescence under hydrostatic pressure
9. In-segregation induced anomalous behavior of band gap and its pressure coefficient in InAlN and InGaN. Theory and Experiment
10. Polymer film-coated high electron mobility transistors, based on GaN heterostructures, as sensors for some benzene derivatives
11. Mass flow and reaction analysis of the growth of GaN layers by HVPE
12. Localized donor states resonant with the conduction band in InN and GaN
13. Microstructure of homoepitaxially grown InGaN/GaN, violet light emitting laser diodes.
14. Modeling of elastic, piezoelectric and optical properties of vertically correlated GaN/AlN quantum dots
15. Influence of n-type doping on light emission properties of GaN layers and GaN-based quantum well structures
16. Built-in electric fields in group III-nitride light emitting quantum structures
17. Application of picosecond four-wave mixing and photoluminescence techniques for investigation of carrier dynamics in bulk crystals and heterostructures of GaN
18. Monte Carlo simulation approach for a quantitative characterization of the band edge in InGaN quantum wells
19. Surprisingly low built-in electric fields in quaternary InAlGaN heterostructures
20. Luminescence transients in highly excited GaN grown by hydride vapor-phase epitaxy
21. Stimulated emission in InGaN/GaN structures with different quantum well width
22. Impact of post-growt thermal annealing on emission of InGaN/GaN multiple quantum wells