Direct Analysis of Stacked Au/Ti/In2O3/Al2O3/p+-Si Transport Mechanisms Using Operando Hard X-ray Photoelectron Spectroscopy

Oxygen transport mechanisms for two different Au/Ti/In2O3/Al2O3/p(+)-Si samples were experimentally evaluated by hard X-ray photoelectron spectroscopy (HAXPES). The deposition temperature for atomic layer deposition of In2O3, as well as the bias voltages applied on the entire stacked structures, were the main parameters used in the work. Chemical analyses of the In2O3 layers deposited at 150 and 200 degrees C for the samples named T_150 and T_200, respectively, revealed a decreased carbon impurity content in the host In2O3 used as a dopant. Ex situ interfacial analysis of In2O3/Al2O3 also indicated oxygen transport from Al2O3 to In2O3. Moreover, we observed that the Ti adhesion metal attracted oxygen and carbon from In(2)O(3 )to form TiO2 and TiC conductive interlayers. Furthermore, operando-HAXPES under an applied bias voltage also revealed that In2O3 underwent phase separation, likely due to variations in the space charge (carriers) around the In2O3/Al2O3 interface for the T_150 sample. Finally, our results emphasize the prominent roles of migration for the ionic oxygen/carbon species and the uncompensated interfacial charge formed by the bias voltage for the metal-semiconductor-oxide stacked structure.