ELECTRICAL-PROPERTIES AND TOPOGRAPHY OF SNO2 THIN-FILMS PREPARED BY REACTIVE SPUTTERING

A scanning tunneling microscopy study of the topology of thin films of SnO2 has been conducted. The films were deposited using de reactive m agnetron sputtering on microscope slides heated to 150 degrees C. No a nnealing treatments were needed. For films of 125 Angstrom to 2 000 An gstrom, the grain size was proportional to the thickness of the films. A study of the O-2 partial pressure showed that films made with a pre ssure in the 10(-6) Torr range gave a quasi-amorphous film. For films made with higher O-2 partial pressure, the grain size increased, Scann ing tunneling microscopy showed a good crystallinity for these films. The transparency was greater than 95% in the 400-800 nm wavelength reg ion for films 125 Angstrom thick. We obtained a film resistivity of 3. 5 x 10(-3) Omega cm, a carrier concentration of 8.9 x 10(19) cm(-3) an d a Hall mobility of 20.77 cm(2) V-1 s(-1). With a relatively good res istivity in the 10(-3) Omega cm range and a mobility around 18 cm(2) V -1 s(-1), we made films having a carrier concentration adjustable by o ne order of magnitude in the 10(19) cm(-3) range.