Anderson disorder related p-type conductivity and metal-insulator transition in β-Ga2O3

• DOI: 10.1016/j.mtphys.2024.101602
• Publication Date: 2024-11-20T18:58:05Z
• Authors: Zeyu Chi; Se-Rim Park; Luka Burdiladze; Tamar Tchelidze; Jean-Michel Chauveau; Yves Dumont; Sang-Mo Koo; Zurab Kushitashvili; Amiran Bibilashvili; Gérard Guillot; Amador Pérez-Tomás; Xin-Ying Tsai; Fu-Gow Tarntair; Ray Hua Horng; Ekaterine Chikoidze
• Keywords: Metal–insulator transition; Anderson Localization

Peer reviewed<br/>With funding from the Spanish government through the "Unit of Excellence Maria de Maeztu" accreditation (CEX2023-001397-M).<br/>The present work is a part of “GALLIA” International Research Project, CNRS, France. GEMaC colleagues acknowledge financial support of French National Agency of Research (ANR), project "GOPOWER", CE-50 N0015-01. This work was partially funded by the France 2030 programme "ANR-11-IDEX-0003″ via Integrative Institute of Materials from Paris-Saclay University - 2IM@UPSaclay. This work was partially funded by EU HORIZON-CL5-2024-D3-01 Safer and More Reliable WBG/UWBG-Based MVDC Power Converters (SAFEPOWER) 101172940. We would acknowledge: GEMaC colleagues Dr.François Jomard and Dr. Estelle Loire contribution with SIMS analysis and David Hrabovsky, Sorbonne University for the PPMS measurements. This work is partially supported by Shota Rustaveli National Science Foundation of Georgia, Grant Number STEM-22-188, the Spanish Maria de Maeztu grant CEX2023-001397-M funded by MICIU/AEI/10.13039/501100011033 and project “OptoFET” (No PID2020-117201RB-C22). This study was also supported by National Science and Technology Council, Taiwan, R.O.C., under the grants Nos: 112-2622-E-A49 -011, 112-2221-E-A49-069-MY3.<br/>The p-type doping is one of the main challenges of the emerging semiconductor β-Ga2O3 technology. Phosphorus (P) implantation has been recently reported as a novel route to achieve p-type conduction on Ga2O3 at room temperature. Here, P-implanted epilayers, grown onto c-plane sapphire revealed a pseudo-metallic behavior (ρ = 1.3–0.3 Ω cm) in the 300–600 K range with a hole carrier concentration of p ⁓ 4–6 × 1018 cm−3 and hole mobility of μ = 1.2–2.1 cm2/(V·s). At sufficiently low temperature, a metal-insulator transition arises together with an increase in the positive magnetoresistance, reaching up to 200 % (9 T) large positive magneto resistance effect at 2 K. It is suggested that an Anderson delocalization model explains the room temperature conduction, and the transition to an insulator state caused by random variation of potential related to the incorporated phosphorous in Ga2O3. We believe that the lack of shallow acceptors can be mitigated by promoting Anderson disorder through the incorporation of a high level of acceptor impurities.<br/>