Amorphous p-type AlSnO thin film by a combustion solution process

Amorphous AlSnO (a-ATO) thin films have been synthesized by a combustion solution process at low temperatures, with the Al:Sn molar ratio of 1:x (x = 11 − 7) in the precursors. The influence of compositions on the structural, optical, and electrical properties of AlSnO (ATO) films were investigated in detail. The X-ray diffraction patterns revealed that all the ATO films are amorphous in nature. All elements were distributed uniformly over the films, regardless of holes formed in the matrix with increasing Al contents. The a-ATO films had an average transmittance over 80% in the visible region, with enlarged optical band gap energies from 3.42 to 3.67 eV at elevated Al contents. Hall-effect measurements identified that weak p-type conductivity could be obtained at the high Al doping levels with Al:Sn ratios higher than 1:9. The realization of p-type a-ATO films by the combustion solution method may open a door to design p-type amorphous-oxide-semiconductor thin-film transistors for transparent electronics.