Degenerate doping in B-Ga₂O₃ Single Crystals through Hf-doping

Journal Article · 12 March 2020 · Semiconductor Science and Technology

DOI: https://doi.org/10.1088/1361-6641/ab75a6 · OSTI ID:1601954

Saleh, Muad  ^[1]; Varley, Joel B. ^[2]; Jesenovec, Jani ^[1]; Bhattacharyya, Arkka  ^[3]; Krishnamoorthy, Sriram  ^[3]; Swain, Santosh ^[1]; Lynn, Kelvin ^[1]

---

1. Washington State Univ., Pullman, WA (United States)
2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
3. Univ. of Utah, Salt Lake City, UT (United States)

n-type conductivity of β-Ga₂O₃ grown from the melt is typically achieved using Sn and Si. In this paper, we experimentally and computationally investigate Hf doping of β-Ga₂O₃ single crystals using UV–vis-NIR absorption and Hall effect measurements and hybrid functional calculations. Unintentionally-doped and Hf-doped samples with a nominal concentration of 0.5at% were grown from the melt using vertical gradient freeze and Czochralski method in mixed Ar + O₂ atmosphere. We demonstrate Hf dopants, predicted to incorporate on the octahedral GaII site as a shallow donor, achieve degenerate doping in β-Ga₂O₃ with a measured electron concentration ~2 × 10¹⁹ cm^-3, mobility 80–65 cm² V^-1 s^-1, and resistivity down to 5 mΩ cm in our samples. The concentration of Hf was measured to be 1.3 × 10¹⁹ atoms cm^-3 using glow discharge mass spectroscopy on doped samples, confirming Hf to be the cause of n-type conductivity (electron concentration ~2 × 10¹⁹ cm^-3).

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 1601954
• Report Number(s): LLNL-JRNL-793748; 993525
• Journal Information: Semiconductor Science and Technology, Vol. 35, Issue 4; ISSN 0268-1242
• Publisher: IOP PublishingCopyright Statement
• Country of Publication: United States
• Language: English