Effect of sequential N ion implantation in the formation of a shallow Mg-implanted p-type GaN layer

• Published in: Journal of applied physics 2024-08, Vol.136 (5)
• Main Authors: Uzuhashi, Jun, Chen, Jun, Tanaka, Ryo, Takashima, Shinya, Edo, Masaharu, Ohkubo, Tadakatsu, Sekiguchi, Takashi
• Format: Article
• Language: English
• Subjects: Cathodoluminescence; Defect annealing; Efficiency; Extreme values; Gallium nitrides; Ion implantation; Scanning transmission electron microscopy
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/5.0216601

An area-selectable Mg doping via ion implantation (I/I) is essential to realize gallium nitride (GaN) based power switching devices. Conventional post-implantation annealing forms considerable defects in the GaN, resulting in extremely low activation efficiency. The recent invention of ultrahigh-pressure annealing (UHPA) has substantially improved the p-type activation efficiency; however, the UHPA causes an unexpected Mg diffusion. Thus, both annealing processes resulted in a much lower Mg concentration in the GaN matrix than the Mg dose. In this study, the effect of a sequential N I/I for p-type Mg-implanted GaN was investigated by the correlative cathodoluminescence, transfer length method, scanning transmission electron microscopy, and atom probe tomography (APT) analyses. APT results have revealed that the sequential N I/I can successfully maintain the Mg concentration in the GaN matrix in the higher range of 1018 cm−3 or more. Our investigation suggests that sequential N I/I is a promising technique to maintain the Mg concentration higher and improve the p-type activation efficiency.