title: Bipolar doping and band-gap anomalies in delafossite transparent conductive oxides.
abstract: Doping wide-gap materials p type is highly desirable but often difficult. This makes the recent discovery of p-type delafossite oxides, CuM(III)O2, very attractive. The CuM(III)O2 also show unique and unexplained physical properties: Increasing band gap from M(III) = Al,Ga, to In, not seen in conventional semiconductors. The largest gap CuInO2 can be mysteriously doped both n and p type but not the smaller gaps CuAlO2 and CuGaO2. Here, we show that both properties are results of a large disparity between the fundamental gap and the apparent optical gap, a finding that could lead to a breakthrough in the study of bipolarly dopable wide-gap semiconductor oxides.
authors.affiliation: National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
authors.forename: Xiliang
authors.initials: X
authors.lastname: Nie
authors.forename: Su-Huai
authors.initials: SH
authors.lastname: Wei
authors.forename: S B
authors.initials: SB
authors.lastname: Zhang