JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, v.139, no.47, pp.17175 - 17180
Abstract
Transparent bipolar semiconductors (TBSCs) are in demand for transparent electronics to serve as the basis for next generation optoelectronic devices. However, the poor carrier controllability in wide-bandgap materials makes the realization of a bipolar nature difficult. Only two materials, CuInO2 and SnO, have been reported as TBSCs. To satisfy demand for the coexistence of transparency and bipolarity, we propose a design concept with three strategies; choice of early transition metals (eTM) such as Y3+ and Zr4+ for improving controllability of carrier doping, design of chemical bonds to obtain an appropriate band structure for bipolar doping, and use of a forbidden band-edge transition to retain transparency. This approach is verified through a practical examination of a candidate material, tetragonal ZrOS, which is chosen by following the criteria. ZrOS exhibits an excellent controllability of the electrical conductivity (10(-7)-10(-2) S cm(-1)), p- or n-type nature with similar to 10(-2) S cm(-1) by Y or F doping, respectively, and optically wide gap (below 10(-4) cm(-1) up to similar to 2.5 eV). This concept provides a new kind of TBSC based on eTM ionic compounds.