AUTHOR=Lee Kwang Jae , Wen Xinyi , Nakazato Yusuke , Chun Jaeyi , Noshin Maliha , Meng Chuanzhe , Chowdhury Srabanti TITLE=A systematic study on the efficacy of low-temperature GaN regrown on p-GaN to suppress Mg out-diffusion JOURNAL=Frontiers in Materials VOLUME=10 YEAR=2023 URL=https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2023.1229036 DOI=10.3389/fmats.2023.1229036 ISSN=2296-8016 ABSTRACT=

Embedding p-type gallium nitride (p-GaN) in Al_xGa_1-xN-based thin films has garnered significant interest as a versatile structure for bandgap engineering such as tunnel/super-junctions or current blocking/guiding functions in electronic devices. However, Mg, a p-GaN dopant, has an undesirable diffusive capacity into the nearby thin films at a high growth temperature (>1,000°C), resulting in structural challenges in device design. This study systematically investigated the low-temperature GaN (LT-GaN) layer regrown on p-GaN that suppresses Mg diffusion according to metal–organic chemical vapor deposition growth conditions. Prototype Al_0.3Ga_0.7N (40 nm)/GaN (140 nm) high-electron-mobility transistors (HEMTs) were regrown with LT-GaN on p-GaN (300 nm), and a high two-dimensional electron gas (2DEG) density of 3.13E12 cm⁻² was achieved by inserting a 100-nm-thick LT-GaN layer grown at 750°C; in contrast, only 1.76E10 cm⁻² 2DEG density was obtained from Al_0.3Ga_0.7N/GaN HEMTs regrown directly on p-GaN (Mg: 4.0E19 cm⁻³). The fabricated Al_0.3Ga_0.7N/GaN HEMTs with 100-nm-thick LT-GaN demonstrated a high drain current density of 84.5 mA/mm with a low on-state resistance of 31 Ω·mm. The Al_xGa_1-xN/LT-GaN/p-GaN platform demonstrated here paves the way for various III-nitride-based structures with embedded p-GaN.