High electron mobility of indium oxide grown on yttria-stabilized zirconia

Abstract

In 2 O 3 heteroepitaxial layers of improved surface morphology and mobility were obtained by pulsed-laser-deposition method supplying proper oxygen to indium ratio on the growing surface, combined with the suppression of thermal decomposition of In2O3 layers. In situ monitoring of reflection high-energy electron diffraction patterns and ex situ monitoring of growth rate of the epilayers grown under different oxygen pressures and growth temperatures revealed that thermal decomposition occurred during the high-temperature growth and the use of significant oxygen pressure could suppress decomposition allowing for an increase in obtainable growth temperatures. As a result of the decomposition control and growth optimization, undoped In2O3 epilayers exhibited atomically flat surfaces, improved Hall mobility of 110cm2∕Vs, and carrier density of 6.6×1018cm−3. The influences of growth and postgrowth conditions on the electrical properties of epilayers were investigated based on charged and neutral impurity scattering models. The origins of the scattering centers of electrons were considered to be the same for both epilayers grown under different growth conditions (oxygen pressure and growth temperature) and annealed in reduced atmosphere after growths, and ionized impurity scatterings such as oxygen vacancy are the most probable candidates; however, postgrowth annealing process under 1atm oxygen was considered to generate another scattering center, leading to the decrease in both mobility and carrier density.