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We present a detailed theoretical analysis of the electronic and optical properties of c-plane InGaN/GaN quantum well structures with In contents ranging from 5% to 25%. Special attention is paid to the relevance of alloy induced carrier localization effects to the green gap problem. Studying the localization length and electron-hole overlaps at low and elevated temperatures, we find alloy-induced localization effects are crucial for the accurate description of InGaN quantum wells across the range of In content studied. However, our calculations show very little change in the localization effects when moving from the blue to the green spectral regime; i.e. when the internal quantum efficiency and wall plug efficiencies reduce sharply, for instance, the in-plane carrier separation due to alloy induced localization effects change weakly. We conclude that other effects, such as increased defect densities, are more likely to be the main reason for the green gap problem. This conclusion is further supported by our finding that the electron localization length is large, when compared to that of the holes, and changes little in the In composition range of interest for the green gap problem. Thus electrons may become increasingly susceptible to an increased (point) defect density in green emitters and as a consequence the nonradiative recombination rate may increase.
Localization lengths of the electrons and holes in InGaN/GaN quantum wells have been calculated using numerical solutions of the effective mass Schrodinger equation. We have treated the distribution of indium atoms as random and found that the result
We have mesured the carrier recombination dynamics in InGaN/GaN multiple quantum wells over an unprecedented range in intensity. We find that at times shorter than 30,ns, they follow an exponential form, and a power law at times longer than 1,$mu$s.
We demonstrate a series of InGaN/GaN double quantum well nanostructure elements. We grow a layer of 2 {mu}m undoped GaN template on top of a (0001)-direction sapphire substrate. A 100 nm SiO2 thin film is deposited on top as a masking pattern layer.
We present an atomistic description of the electronic and optical properties of $text{In}_{0.25}text{Ga}_{0.75}$N/GaN quantum wells. Our analysis accounts for fluctuations of well width, local alloy composition, strain and built-in field fluctuations
In this work we present a detailed analysis of the interplay of Coulomb effects and different mechanisms that can lead to carrier localization effects in c-plane InGaN/GaN quantum wells. As mechanisms for carrier localization we consider here effects