We studied the adsorption of liquids over the surface of InGaN quantum well based wide band-gap devices and found that the immersion in certain liquids has noticeable effects on the optical blinking phenomena. We used two samples with different indium concentrations, emitting on the green and blue range, and immersed them while under direct illumination with 365~nm UV light. We found that especially water and ethanol provoked evident optical variations compared to observation in air. While blinking spots can be observed irrespective of the In concentration, their contrast and luminosity increased for samples with the emission in the 510~nm range, rather than for those in the 460~nm. Based on these results, we put forward the hypothesis that the presence of liquids induces the formation of radiative centers, possibly complexes related to intrinsic defects binding with adsorbed impurities, such hydrogen or oxygen.
The blinking phenomenon in InGaN single quantum wells is a phenomenon where localized photoluminescence changes over time. Understanding its physics is important for the manufacture of more efficient light emission diodes. We present a study using two InGaN single quantum well samples, emitting at 460 and 510 nm wavelength, respectively. We confirmed that the luminescence intensity fluctuates in localized blinking regions, and we found that these optical variations are not random but are instead correlated in pairs, with either positive or negative coefficient, to a distant reference blinking point. Measurements were performed to obtain standard deviation and cross-correlation maps. Invoking the quantum confined Stark effect, we realized a simple phenomenological model that shows how charge carriers are exchanged among pairs of adjacent opposite correlation regions. As a result, it is suggested that the phenomenon is caused by fluctuations in the number of these exchanged carriers. Our model gives an explanation for the blinking phenomenon in InGaN single quantum wells, and it is important for a deeper understanding to InGaN-based materials.
Impurities and their complexes with intrinsic point defects, e.g vacancies, can alter the opto-electronic properties of semiconductors. Among such impurities, helium is incorporated into GaN by ion implantation, for wafer splitting and for device isolation purposes. Yet, despite the technological importance of such impurity, it is not known whether or not He is electrically active in GaN or what its impact on n- or p-type dopants is. For this reason, we carried out a density functional theory (DFT) study of substitutional He and related complexes (vacancies and dopants) in wurtzite GaN. We employed the generalized gradient approximation (GGA) and overcame the band gap energy understimation, by a posteriori corrections. It is found that He is unstable at N-sites, moving to interstitial sites and forming a N vacancy (VN). This was observed for the case of substitutional He and for He complexed with n- or p-type dopants. The formation of VN, in such defects, gives rise to donor states close to the valence band edge (EV). On the other hand, the presence of a gallium vacancy (VGa) leads to the formation of an energetically stable complex that gives rise to acceptor states close to the conduction band edge (EC). Our findings are then discussed in the light of previous experimental reports on GaN device isolation.
Chlorine‐based reactive ion etching (RIE) is a fundamental processing step for the manufacturing of GaN semiconductor devices. As impurities can be unintentionally incorporated in the crystal during processing, the electronic properties of chlorine in GaN are investigated. Density functional theory calculations of substitutional Cl and related complexes (with a vacancy or a dopant) are carried out. It is found that Cl and its complexes explain the reported effects of Cl RIE‐treated GaN on hole density and ohmic contact resistivity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.