Hole mobility enhancement in high-Al-content p-type AlGaN via site-selective Mg doping

Abstract Achieving high hole conductivity in high-Al-content p-type AlGaN remains a critical challenge for deep-ultraviolet optoelectronics. In this work, we systematically investigate the electronic structures and hole transport mechanisms in three Mg-doped Al₀.₇₅Ga₀.₂₅N configurations: alloy, (GaN)₁/(AlN)₃ superlattice (SL), and GaN quantum dots (QD) by performing the firstprinciples calculations. While the alloy configuration exhibits the highest hole mobility, it is limited by a large activation energy (367 meV). The QD configuration shows the lowest activation energy but is plagued by an extremely high ionized impurity (IMP) scattering rate, resulting in the poorest mobility (0.01 cm² V⁻¹ s⁻¹). Consequently, the SL configuration presents a balanced and promising candidate. We further demonstrate that the hole transport in the SL can be optimized through site-selective Mg doping within the AlN layer, which concurrently reduces the hole effective mass, suppresses the dominant IMP and polar optical phonon scattering rates by over an order of magnitude, and lowers the activation energy, thereby enhancing the mobility to increased to 18.9 cm² V⁻¹ s⁻¹. This study elucidates the carrier scattering mechanisms across different doping architectures and proposes a feasible doping-site-engineering to overcome the key limitation in p-type conductivity of high-Alcontent AlGaN, paving the way for efficient deep-ultraviolet optoelectronic devices.