Multi-step in situ interface modification method for emission enhancement in semipolar deep-ultraviolet light emitting diodes

Abstract

Semipolar III-nitrides have attracted increasing attention in applications of optoelectronic devices due to the much reduced polarization field. A high-quality semipolar AlN template is the building block of semipolar AlGaN-based deep-ultraviolet light emitting diodes (DUV LEDs), and thus deserves special attention. In this work, a multi-step in situ interface modification technique is developed for the first time, to our knowledge, to achieve high-quality semipolar AlN templates. The stacking faults were efficiently blocked due to the modification of atomic configurations at the related interfaces. Coherently regrown AlGaN layers were obtained on the in situ treated AlN template, and stacking faults were eliminated in the post-grown AlGaN layers. The strains between AlGaN layers were relaxed through a dislocation glide in the basal plane and misfit dislocations at the heterointerfaces. In contrast, high-temperature ex situ annealing shows great improvement in defect annihilation, yet suffers from severe lattice distortion with strong compressive strain in the AlN template, which is unfavorable to the post-grown AlGaN layers. The strong enhancement of luminous intensity is achieved in in situ treated AlGaN DUV LEDs. The in situ interface modification technique proposed in this work is proven to be an efficient method for the preparation of high-quality semipolar AlN, showing great potential towards the realization of high-efficiency optoelectronic devices.

Temperature-Dependent Optical Behaviors and Demonstration of Carrier Localization in Polar and Semipolar AlGaN Multiple Quantum Wells

“…Overall, the in situ thermal-treated sample shows much narrower XRD RC linewidths, suggesting a lower defect density and better crystal quality than the HTA sample. The efficient blocking and annihilation of stacking faults in the in situ-treated sample can be ascribed to the interface modification process as previously demonstrated in our work [13]. Specifically, the stacking faults were efficiently blocked due to the modification of atomic configurations at the related interfaces.…”

“…However, the ex situ annealing technique poses a growth because large residual strains are built up. Rece situ treatment technique that greatly improves the crysta on the semipolar AlN template, ultimately achieving a s nescence intensity [13]. The in situ treatment technique cient method for the preparation of high-quality semipo toward the realization of high-efficiency optoelectronic d ing of the optical behaviors of the semipolar DUV-LED g situ-annealed AlN template is strongly desired.…”

“…Meanwhile, the carrier localization also depends on o factors, such as composition uniformity and quantum well/barrier width [21,24,25] the thermal annealing process, columnar AlN prepared films coalesced into a uniform thin sities. However, the ex situ annealing techniq growth because large residual strains are bu situ treatment technique that greatly improve on the semipolar AlN template, ultimately a nescence intensity [13]. The in situ treatment cient method for the preparation of high-qua toward the realization of high-efficiency opto ing of the optical behaviors of the semipolar D situ-annealed AlN template is strongly desire Optical behaviors are critically importan which has long been responsible for the im based blue LED despite its high density of th from defect-related nonradiative recombinati dom alloy fluctuation [16], and variation in Q internal quantum efficiency (IQE).…”

“…However, the ex situ annealing technique poses a challenge to the subsequent LED growth because large residual strains are built up. Recently, our group developed an in situ treatment technique that greatly improves the crystal quality while relaxing the strain on the semipolar AlN template, ultimately achieving a strong enhancement of the luminescence intensity [13]. The in situ treatment technique proposed is proven to be an efficient method for the preparation of high-quality semipolar AlN, showing great potential toward the realization of high-efficiency optoelectronic devices.…”

High-Temperature Annealing Assisted High-Quality Semipolar (112̅2) AlN Film for Vacuum Ultraviolet Detectors

“…In recent years, high-temperature annealing (HTA) of sputtered AlN films has been widely investigated to promote the development of high-quality nitride films on different face sapphire substrates. − HTA and regrowth processes are adopted as stable and effective methods in the realization of high luminous efficiency LEDs. , For c-plane nitride materials and devices, Weyers et al revealed that the performance of DUV LEDs could be significantly improved due to strain management and defect reduction using two annealing steps . Wang et al studied the power enhancement of the 265 nm DUV-LED flip-chip based on an annealed hydride vapor phase epitaxy-AlN (HVPE-AlN) .…”