Abstract
In this study, systematic structural design was investigated numerically to probe into the cross-relating influences of n-AlGaN layer, quantum barrier (QB), and electron-blocking layer (EBL) on the output performance of AlGaN deep-ultraviolet (DUV) light-emitting diodes (LEDs) with various Al compositions in quantum wells. Simulation results show that high-Al-composition QB and high-Al-composition EBL utilized separately are beneficial for the enhancement of carrier confinement, while the wall-plug efficiency (WPE) degrades dramatically if both high-Al-composition QB and EBL are existing in a DUV LED structure simultaneously. DUV LEDs may be of great optical performance with appropriate structural design by fine-tuning the material parameters in n-AlGaN layer, QB, and EBL. The design curves provided in this paper can be very useful for the researchers in developing the DUV LEDs with a peak emission wavelength ranging from 255 nm to 285 nm.
Highlights
In AlGaN deep-ultraviolet (DUV) light-emitting diodes (LEDs), there are several critical challenges including lack of lattice-matched substrate, nature of lattice-mismatched AlGaN material system, and difficulty of sufficient hole activation in high-Al-composition p-AlGaN layers [1,2,3,4]
The DUV LED structure referred to the literature published by Yan et al [18] is used as a reference, which has a peak emission wavelength of 284.5 nm at 60 mA
This numerical study provides a systematic structural design to probe into the influences of n-AlGaN layer, quantum barrier (QB), and electron-blocking layer (EBL) on the output performance of AlGaN DUV LEDs in various emission spectral ranges
Summary
In AlGaN deep-ultraviolet (DUV) light-emitting diodes (LEDs), there are several critical challenges including lack of lattice-matched substrate, nature of lattice-mismatched AlGaN material system, and difficulty of sufficient hole activation in high-Al-composition p-AlGaN layers [1,2,3,4]. A thorough study on structural design of the DUV LEDs, which may severely affect the output performance of DUV LEDs, is still demanded. The mechanism of carrier transport in p-type layers was theoretically investigated, which revealed that the large potential barrier in the valence band of heterojunctions could be a critical issue obstructing the transport and injection of holes especially when the Al composition in the AlGaN EBL is high [14]. One multi-layer staircase hetero-structure was proposed for the p-type region of DUV LEDs. the materials of n-AlGaN layer, quantum barrier (QB), and EBL were investigated to probe into the capability of carrier confinement of DUV LEDs in our previous research [15,16]. The physical origins such as the carrier transport, carrier confinement, and interband transitions of the relevant characterization are analyzed in detail
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