BAND ALIGNMENT OF ULTRATHIN GIZO/SiO2/Si HETEROSTRUCTURE DETERMINED BY ELECTRON SPECTROSCOPY

Abstract

Amorphous GaInZnO (GIZO) thin films are grown on SiO2/Si substrate by the RF magnetron sputtering method. By thecombination of measured band gaps from reflection energy loss spectroscopy (REELS) spectra and valence band fromX-ray photo-electron spectroscopy (XPS) spectra, we have demonstrated the energy band alignment of GIZO thin films.The band gap values are 3.2 eV, 3.2 eV, 3.4eV and 3.6eV for the concentration ratios of Ga: In: Zn in GIZO thin filmsare 1:1:1, 2:2:1, 3:2:1 and 4:2:1, respectively. These are attributed to the larger band gap energy of Ga2O3 comparedwith In2O3 and ZnO. The valence band offsets (ΔEv) decrease from 2.18 to 1.68 eV with increasing amount of Ga inGIZO thin films for GIZO1 to GIZO4, respectively. These experimental values of band gap and valence band offsetwill provide the further understanding in the fundamental properties of GIZO/SiO2/Si heterostructure, which will beuseful in the design, modeling and analysis of the performance devices applications.

Keywords

• band alignment
• band gap
• GIZO
• REELS
• XPS