Degenerate doping in β-Ga2O3 single crystals through Hf-doping. (12th March 2020)

• Record Type: Journal Article
• Authors: Saleh, Muad; Varley, Joel B; Jesenovec, Jani; Bhattacharyya, Arkka; Krishnamoorthy, Sriram; Swain, Santosh; Lynn, Kelvin
• Is Part Of: Semiconductor science and technology. Volume 35:Number 4(2020)
• Publication Date: 2020-03-12
• Subjects: β-Ga2O3 -- crystal growth -- hybrid functionals; Semiconductors -- Periodicals; 621.38152
• DOI: 10.1088/1361-6641/ab75a6
• Languages: English
• ISSNs: 0268-1242

Abstract

Abstract: n-type conductivity of β -Ga2 O3 grown from the melt is typically achieved using Sn and Si. In this paper, we experimentally and computationally investigate Hf doping of β -Ga2 O3 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 -Ga2 O3 with a measured electron concentration ∼2 × 10 19 cm −3, mobility 80–65 cm 2 V −1 s −1, and resistivity down to 5 mΩ cm in our samples. The concentration of Hf was measured to be 1.3 × 10 19 atoms cm −3 using glow discharge mass spectroscopy on doped samples, confirming Hf to be the cause of n-type conductivity (electron concentration ∼2 × 10 19 cm −3 ).