Degenerate p-type conductivity in wide-gap LaCuOS1−xSex (x=0–1) epitaxial films

Epitaxial films of ${\mathrm{LaCuOS}}_{\text{1−x}}{\mathrm{Se}}_x$ $\text{(x=0–1)}$ solid solution were grown on MgO (001) substrates and their electrical and optical properties were examined. Sharp emission due to room-temperature exciton with binding energy of $\text{∼50\hspace{0.17em}}\mathrm{meV}$ is observed for all $x$ values. Hall mobility becomes large with an increase in the Se content and it reaches $\text{8.0\hspace{0.17em}}{\mathrm{cm}}^2{\mathrm{V}}^{\text{−1}}{\mathrm{s}}^{\text{−1}}$ in LaCuOSe, a comparable value to that of $p$ -type GaN:Mg. Doping of ${\mathrm{Mg}}^{\text{2+}}$ ions at ${\mathrm{La}}^{\text{3+}}$ sites enhances a hole concentration up to ${\text{2.2×10}}^{20}\hspace{0.17em}{\mathrm{cm}}^{\text{−3}},$ while maintaining the Hall mobility as large as $\text{4.0\hspace{0.17em}}{\mathrm{cm}}^2{\mathrm{V}}^{\text{−1}}{\mathrm{s}}^{\text{−1}}.$ Consequently, a degenerate $p$ -type electrical conduction with a conductivity of $\text{140\hspace{0.17em}}{\mathrm{S cm}}^{\text{−1}}$ was achieved.