Abstract
The band structure of the dilute-As GaNAs material is explained by the hybridization of localized As-impurity states with the valance band structure of GaN. Our approach employs the use of Density Functional Theory (DFT) calculated band structures, along with experimental results, to determine the localized As-impurity energy level and coupling parameters in the band anti-crossing (BAC) k ∙ p model for N-rich alloys. This model captures the reduction of bandgap with increasing arsenic incorporation and provides a tool for device-level design with the material within the context of the k ∙ p formalism. The analysis extends to calculating the effect of the arsenic impurities on hole (heavy, light and split-off) effective masses and predicting the trend of the bandgap across the entire composition range.
Highlights
Major breakthroughs in solid-state lighting and energy efficiency applications have been enabled in recent decades through thorough investigation of the class of III-nitride semiconductors, including GaN, InN, AlN, and their alloys with one another[1,2]
The dilute-As GaNAs material system is best-modelled with the parameters of localized impurity energy at EAs = −0.39 eV and a coupling constant CGaNAs = 2.57 eV
The model predicts large split-off energies (>1 eV), compared to both that of GaN30 and GaAs35, at even low levels of arsenic incorporation (~1.56%). This prediction is supported by the Density Functional Theory (DFT)-calculations[11], which indicate a large splitting of the split-off band from the heavy hole and light hole bands in the dilute-As regime
Summary
Major breakthroughs in solid-state lighting and energy efficiency applications have been enabled in recent decades through thorough investigation of the class of III-nitride semiconductors, including GaN, InN, AlN, and their alloys with one another[1,2]. Advancements in both material epitaxy methods, along with new, innovative approaches for device level design, have enabled the production of highly efficient light emitting diodes (LED) devices[3,4]. Using DFT results to fit our model allows for the atomistic description of the electronic states in the material to be transformed into useful parameters for nanoscale device level design
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