Abstract: P-type transparent conducting indium-tin oxide thin films were successfully prepared by spray pyrolysis and characterized by XRD, Hall and UV-Visible transmission spectra. The results show that with small
In/Sn ratio, the films are in rutile SnO₂ structure, and the films show n-type conductivity. With In/Sn ratio in the range of 0.06～0.25 and process temperature above 550℃, the films are still in
rutile structure, but the conductivity type changes to p-type. For films with In/Sn ratio >0.3, conductivity type changes back to n-type. The process temperature is also an important parameter to the films.
With In/Sn=0.2, the films show n-type for T<550℃, and change to p-type for T>550℃. The hole concentration saturates at T=700℃, with hole concentration as high as 4×10¹⁸cm^-3.
Besides, all the films show transmission as high as 80% in the visible region.

Key words: SnO₂, transparent conducting, spray pyrolysis, p-type doping