First-principles exploration of defect-pairs in GaN

Abstract

Using first-principles calculations, we explored all the 21 defect-pairs in GaN and considered 6 configurations with different defect-defect distances for each defect-pair. 15 defect-pairs with short defect–defect distances are found to be stable during structural relaxation, so they can exist in the GaN lattice once formed during the irradiation of high-energy particles. 9 defect-pairs have formation energies lower than 10 eV in the neutral state. The vacancy-pair VN–VN is found to have very low formation energies, as low as 0 eV in p-type and Ga-rich GaN, and act as efficient donors producing two deep donor levels, which can limit the p-type doping and minority carrier lifetime in GaN. VN–VN has been overlooked in the previous study of defects in GaN. Most of these defect-pairs act as donors and produce a large number of defect levels in the band gap. Their formation energies and concentrations are sensitive to the chemical potentials of Ga and N, so their influences on the electrical and optical properties of Ga-rich and N-rich GaN after irradiation should differ significantly. These results about the defect-pairs provide fundamental data for understanding the radiation damage mechanism in GaN and simulating the defect formation and diffusion behavior under irradiation.

The Electronic Properties of Chlorine in GaN: An Ab Initio Study

“…[ 18,19 ] However, in n‐type GaN, is neutral and divacancies are acceptors. [ 2,42 ] In addition, our results support the reported increase of , following Cl‐RIE. As a matter of fact, if Cl is incorporated in GaN, and are acceptors in n‐GaN and can lead to donor compensation, thus worsening the ohmic behavior.…”

Defects and Reliability of GaN‐Based LEDs: Review and Perspectives

“…While the probability of V N formation in p‐type GaN is higher than that of Ga‐vacancy (V Ga ), [ 55 ] this latter species was identified as the dominant acceptor level in hydride vapor‐phase epitaxy (HVPE) GaN‐based LEDs. [ 56 ] Despite their energy level is close to the valence band, mostly reported within the 0.59 eV < E T − E v < 1 eV range, the presence of V Ga can lead to a reduction in the optical efficiency of LEDs because 1) it may prevent hole transport inside the active region, [ 17 ] 2) induce the formation of complexes, such as V Ga –3H, V Ga –2H, V Ga –O N –2H, V Ga –O N –H, V N –V N , which act as NRRCs [ 57,58 ] and/or release hydrogen during device operation. [ 59 ]…”

“…which act as NRRCs [57,58] and/or release hydrogen during device operation. [59] The identified impurities collected in our catalog are: Mg, H, Si, C, Fe, and O.…”

Effect of Oxygen and Aluminum Incorporation on the Local Structure of GaN Nanowires: Insight from Extended X-ray Absorption Fine Structure Analysis

“…In the present study, the configurations investigated in Tables 3 and 4, were proposed and discussed in the literature on experimental and theoretical works. [43][44][45][46][47][48][49][50][51][52] In the cases of high oxygen concentration, it is favorable for the oxygen to occupy the VN and to bind to VGa, which is randomly distributed within the bulk. 50 .…”