Electronic Doping in Porous Nano-Crystalline ZnO Films

Porous nano-crystalline ZnO films were prepared in sol-gel technique, sing spin coating and sintering at modest temperatures. The films consist of loosely-packed ZnO clusters. For films with clusters smaller than {approximately} 50 {angstrom} the authors find a blue-shifted absorption edge indicative of quantum confinement in the clusters. The electronic properties of the films are largely controlled by surface processes. The authors have studied photo-induced conductance changes due to CO{sub 2} desorption using mass spectrometry and concomitant electrical measurements. ZnO and other oxides have been studied as a substrate for solar absorbers.