Synthesis and control of conductivity of ultraviolet transmitting β-Ga2O3 single crystals

TLDR

The study is motivated by the expectation that heavily doped β‑Ga₂O₃ can transmit KrF laser light. β‑Ga₂O₃ single crystals were grown by floating‑zone method, with conductivity along the b axis tuned from <10⁻⁹ to 38 Ω⁻¹ cm⁻¹ by varying the growth atmosphere, and Sn‑doped feed rods produced highly conductive crystals even under oxidative conditions. Optical measurements showed that a 0.32 mm β‑Ga₂O₃ crystal is transparent across visible and UV wavelengths, achieving 20 % transmittance at 266 nm, and that its band gap widens as carrier concentration increases.

Abstract

β- Ga 2 O 3 single crystals were grown by the floating zone method and their conductivity along the b axis was controlled from &amp;lt;10−9 to 38 Ω−1 cm−1 by changing the growth atmosphere. By using feed rods doped with Sn, the grown crystal became highly conductive even under oxidative atmosphere. The optical transmission spectra showed that the β-Ga2O3 single crystal with 0.32 mm was transparent in the visible and ultraviolet region, with 20% transmittance at the fourth-harmonic wave of the Nd:YAG laser (266 nm). The band-gap widening was observed with the increasing of the carrier concentration. It is expected that the light of the KrF laser can be transmitted in the heavily doped β-Ga2O3.