By Valentina De Vincenti
Professor Xiaohang Li's Visiting Student Research Internship Program (VSRP) intern, Muwei Zhang has recently published his first-author paper "Structural and electronic properties of wurtzite BxAl1_xN from first-principles calculations" on the Physica Status Solidi (b) Journal. 
In May 2017, Zhang completed the VSRP, an opportunity for qualified baccalaureate and post-baccalaureate students to visit the King Abdullah University of Science and Technology (KAUST) and do hands-on research with faculty mentors in selected areas of basic and applied research projects. Zhang's cutting-edge paper is an exceptional outcome of KAUST's Visiting Student Research Program (VSRP), which was launched in January 2014. Of the one hundred sixty-one who applied, 48% VSRP Research Interns are currently KAUST degree candidates in MS/PhD and PhD degree programs.
Under Professor Li's supervision in the Advanced Semiconductor Laboratory, Zhang investigated the high optoelectric efficiency of a Wurtzite (WZ) III-Nitride novel material for direct applications in UV devices. Previous studies on aluminum-based III-Nitride materials have shown excellent structural and electronic properties with tunable direct bandgap which can cover a broad ultraviolet (UV) spectral region (200-300nm). Despite other investigations also highlighted the increase in the optoelectric active area of the device, where UV light emission could be enhanced by four times by incorporating Boron (B), but they lack of any direct empirical demonstration.
Based on density functional theory (DFT), the team instead systematically studied the structural and electronic properties of boron-based WZ III-nitride materials. On varying the material composition parameters, the bandgap, density state and effective mass were proved, showing that the direct to indirect bandgap occurred at B equaling 12%. The bandgap exhibits a high dependence on the B composition, thus desirable for low-absorption optical structures.
Results also showed that structural variation of the upper valence band occurs on increasing or lowering the B composition from the desirable 12% chemical threshold. A higher B percentage will cause crystal covalence while B minor incorporation will affect the curvature increase of the band and thus the heavy hole effective mass.
Zhang was a senior student at Huazhong University of Science and Technology (HUST) in Wuhan, Hubei China, with major in Electronics Science & Technology. His academic curriculum shows his keen interest in photonics, with projects on the feasibility of lead-sulfide-quantum-dots being gas sensors as part of his Computational Materials Science Course Project 2016. Before that, he took part in the Xilinx FPGA Design Competition 2015 to design the simple oscilloscope based on the PWM (Pulse-Width Modulation). He was also the Group leader of the Electronic Ceramics Laboratory for the National College Students Innovation Project about PTC effect.