Band alignment study and plasmon generation at dual ion-beam sputtered Ga:ZnO/ Ga:MgZnO heterojunction interface

Abstract

A flat band offset at 3 atomic% Ga-doped ZnO (GZO)/1 atomic% Ga-doped Mg0.05Zn0.95O (GMZO) interface is obtained with valence and conduction band offset values of -0.045 and -0.065 eV, respectively. The materials are grown by dual ion-beam sputtering (DIBS) system, and the values of band offsets at the interface are calculated by ultraviolet photoelectron spectroscopy measurement. It is observed that the band offset can be further tuned by suitable band-gap engineering by changing the elemental composition of Mg and Ga in ZnO or by altering DIBS growth parameters. Moreover, generation of plasmons in individual GZO and GMZO films due to the formation of metal and metal oxide nanoclusters are observed. This is promising in terms of increasing the efficiency of the solar cell by increasing optical path length in the absorbing layer by light scattering and trapping mechanism.