【Member Papers】Hong Kong University Science and Technology (Guangzhou) --- Exploration of p-type conductivity in β-Ga₂O₃ through Se-Mg hyper co-doped: An ion implantation approach

      Researchers from the Hong Kong University of Science and Technology (Guangzhou) have published a dissertation titled "Exploration of p-type conductivity in β-Ga₂O₃ through Se-Mg hyper co-doped: An ion implantation approach" in Materials Today Advances.

Abstract

      As β-Ga₂O₃ continues to advance, achieving stable p-type doping has become a key research focus. This study proposes a method to introduce defect energy levels near the conduction band and acceptor doping elements to achieve p-type doped β-Ga₂O₃. We utilized ion implantation to achieve co-doped Ga₂O₃ with Se and Mg elements, employing a 50 kV acceleration voltage to reach a peak purity concentration depth. The concentrations of Se and Mg were quantified, with the highest concentrations reaching 2.35 × 10²²/cm³ (Se) and 8.99 × 10²¹/cm³ (Mg), consistent with simulation results. After implantation, the Se-Mg co-doped β-Ga₂O₃ underwent rapid thermal annealing at 850 °C in an oxygen environment to mitigate implantation damage. By adjusting the Se and Mg implantation dose, we could slightly tune the bandgap from 4.42 to 4.37 eV. Experimental characteristics revealed valence band maximum values and exhibited potential p-type behavior achieved by Se-Mg co-doping. Hall measurements indicated probable p-type conductivity. However, further verification is required. Additionally, first-principles density functional theory simulations provided calculations of substitutional defect formation energies and Fermi levels within the β-Ga₂O₃ lattice, further elucidating the causes of electronic structure changes induced by doping.