Activation of implanted Si, Ge, and Sn donors in high-resistivity halide vapor phase epitaxial β-Ga2O3:N with high mobility.

Activation of implanted donors into a highly-resistive, nitrogen-doped homoepitaxial β-Ga₂O₃ has been investigated. Nitrogen acceptors with the concentration of ∼10¹⁷ cm⁻³ were incorporated during epitaxial growth yielding low-doped (net donor concentration <10¹⁴ cm⁻³) films subsequently implanted with Si, Ge, and Sn. Upon Ohmic contact formation to the implanted regions, sheet resistance values of 314, 926, and 1676 Ω/sq were measured at room temperature for the Si-, Ge-, and Sn-implanted samples, respectively. Room temperature Hall measurements resulted in sheet carrier concentrations and Hall mobilities of 2.13 × 10¹⁴ /93, 8.58 × 10¹³/78, and 5.87 × 10¹³/63 cm²/(V s), respectively, for these three donor species. Secondary ion mass spectroscopy showed a volumetric dopant concentration of approximately 2 × 10¹⁹ cm⁻³ for the three species, resulting in carrier activation efficiencies of 64.7%, 40.3%, and 28.2% for Si, Ge, and Sn, respectively. Temperature-dependent Hall effect measurements ranging from 15 to 300 K showed a nearly constant carrier concentration in the Si-implanted sample, suggesting the formation of an impurity band indicative of degenerate doping. With a bulk carrier concentration of 1.3 × 10¹⁹ cm⁻³ for the Si implanted sample, a room temperature mobility of 93 cm²/(V s) is among the highest reported in Ga₂O₃ with a similar carrier concentration. The unimplanted Ga₂O₃:N regions remained highly resistive after the surrounding areas received implant and activation anneal. These results open the pathway for fabricating Ga₂O₃ devices through the selective n-type doping in highly resistive epitaxial Ga₂O₃. [ABSTRACT FROM AUTHOR]