Developing cathode materials with high specific capability and excellent electrochemical performance is crucial for the advancement of aluminum-ion batteries, which leverage the high theoretical energy density of aluminum metal anodes. In this paper, we investigated the interaction of AlCl4 cluster and Al atom with AlN (-100) and (001) monolayer using density functional theory (DFT) to assess the applicability of AlN as cathode material for aluminum-ion batteries. The results show that the AlN (001) monolayer is the most effective for adsorbing and accommodating AlCl4 clusters. Moreover, the AlN (001) monolayer maintains metallic behavior at different concentrations of the AlCl4 cluster, laying the foundation for its battery application. The theoretical storage capacity of the AlCl4 cluster is 105.93 mAhg-1, which exceeds that of the Al/graphite battery. The formation energy of AlCl4-intercalated AlN compounds is -2.74 eV, and the intercalant gallery height is moderate. Furthermore, the diffusion barrier of 0.19 eV for AlCl4 cluster between the AlN (001) monolayer provides high rate capability. The results indicate that AlN monolayer may be a potential cathode material for aluminum-ion batteries.

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A significant issue for GaN-based high-electron-mobility transistors (HEMTs) in high power devices is the material defect, particularly the defect states generated by the defects, which has a negative impact on the device carrier concentration and carrier transport. Based on density functional theory (DFT), we investigate the microscopic properties of different type point vacancies in the AlGaN/GaN heterojunction. It is found that N vacancy introduces defect states near the conduction band minimum (CBM) of the GaN layer and AlGaN/GaN interface. Ga and Al vacancies introduce defect states near the valence band maximum (VBM) in bulk and interface of AlGaN/GaN heterojunction. Moreover, Al vacancy is more likely to be an effective candidate for acceptor defect than Ga vacancy. We further study several AlGaN/GaN interface passivation schemes by introducing F, V group element P, and III group element B at the AlGaN/GaN heterojunction interface to analyze the passivation mechanism. According to the results of the passivation models, B passivation of Ga and Al vacancies is an effective method to completely remove the defect states from Ga and Al vacancy defects. Combining the III and V groups elements into the passivated process may be effective in achieving high-quality AlGaN/GaN heterojunction interface for the future GaN-based HEMTs fabrication.