【Member Papers】Dr. Zha Xianhu of Shenzhen Pinghu Laboratory Has Published Scientific Research Results in Internationally Renowned Journals

      Aiming at the difficulty of β phase Gallium Oxide p type conduction, the fourth-generation material device research group of Shenzhen Pinghu Laboratory investigated the regulation mechanism of β phase Gallium Oxide band structure by solid solution of different metal elements. The results that " Effect of Alloying Metal Elements on the Valence Band of β‑Ga₂O₃: A First-Principles Study" have been published in The Journal of Physical Chemistry Letters. Dr. Zha Xianhu is the first author, Wan Yuxi and Zhang Daohua are the corresponding authors, and Li Shuang is the co-author.

      β phase Gallium Oxide is a highly concerned semiconductor material for power devices due to its ultra-wide semiconductor bandgap and economically mature preparation methods. However, P-type conduction of Gallium Oxide is still challenging due to its low valence band energy level and high hole mass. How to achieve P-type doping and prepare Gallium Oxide p-n homojunction with higher avalanche ability and overcurrent stability is an important direction that needs breakthrough. At present, the main strategies to achieve β-phase Gallium Oxide P-type doping are the schemes of size effect, defect regulation, non-equilibrium kinetics and solid solution enhanced valence band top energy level.

      The regulation of the valence band structure of β phase Gallium Oxide by solid solution of 49 different metal elements M was investigated by first principles. It is found that the structure and energy band of the solid solution are closely related to the number of families of M in the periodic table, and a total of 14 kinds of solid solutions (M is the elements of groups 3,9,13 and 15, as well as Be, Cr and Fe) show semiconductor properties. The valence band top energy of Rh, Ir, Sb and Bi solid solutions is more than 1 electron volt higher than that of β phase Gallium Oxide. The band dispersion relationship near the top of valence band of most solid solutions becomes steeper, especially for M group 13 and 15 elements, the corresponding hole effective mass decreases significantly. This work provides theoretical guidance for the experimental study of β phase Gallium Oxide P-type doping. Based on the reduced hole mass and the increased valence band top level, P-type conduction of Gallium Oxide solid solution will be easily achieved, and the performance of power devices can be improved.

FIG. 1. (a) Periodic table of the elements. The examined solidly soluble metal element M is shown in the dark cyan region; (b) Band alignment diagram of a semiconductor β-phase Gallium Oxide solid solution, where M replaces the central GA-site atom of the octahedron on the left, and MGa-II, where M replaces the central GA-site atom of the tetrahedron on the right.

Figure 2. The average hole effective mass of the conductivity of semiconductor MGa-I(M=Sc, Y, La, Cr, Co, Rh, Ir, Ga, In, Tl, Sb, Bi) and MGa-II(M=Be, Al, Fe) solid solutions. The red horizontal dotted line indicates the hole mass of β phase Gallium Oxide.

DOI: 

10.1021/acs.jpclett.4c03493