Shallow donor state of hydrogen in In_2O_3 and SnO_2: Implications for conductivity in transparent conducting oxides

摘要

Muonium, and by analogy hydrogen, is shown to form a shallow-donor state in In_2O_3 and SnO_2. The paramagnetic charge state is stable below ～50 K in In_2O_3 and ～30 K in SnO_2 which, coupled with its extremely small effective hyperfine splitting in both cases, allows its identification as the shallow-donor state. This has important implications for the controversial issue of the origins of conductivity in transparent conducting oxides.