Investigation On Optical And Electrial Characteristics Of Metal-Doped SnO2Films Deposited By Radio Frequence And Direct Current Co-Sputtering

Transparent conductive oxide thin films play an important role in optoelectronic device applications because of its quasimetal resistance and high transmittance in the visible range, high reflectivity in the infrared range and semiconductor properties. SnO2film as a kind of excellent transparent conductive oxide thin film, have been widely applied in solar cell, thermo-electric materials, transparent electrode materials and gas sensitive materials because of its good transparency in the visible light region, low absorption coefficient in the ultraviolet region, low resistivity, stable chemical properties, and strong resistant ability to acids and alkalis at room temperature.Firstly, SnO2films are deposited on Si (100) and glass substrates at room temperature using radio frequency (RF) reactive magnetron sputtering method. The optimal deposition conditions are obtained by changing the experimental parameters. For Si (100) substrates, the deposition power is120W, the ratio of argon and oxygen5:1, the deposition pressure0.4Pa, the deposition time90min; for glass substrates, the deposition power is120W, the ratio of argon and oxygen4:1, the deposition pressure0.4Pa, the deposition time75min. On optimum experimental conditions, the crystallinity of the SnO2film deposited on Si substrate is higher than that on glass substrate, and the compact surface with uniform crystal particles is obtained for the SnO2f ilms deposited on Si substrate. The reflectance and transmittance of films are measured by ultraviolet visible spectrophotometer. The average transmittance of the SnO2film deposited on glass substrates is82.8%. Photoluminescence spectra show the light emission as a single band, and maximum value is located near340and430nm.Secondly, under optimum preparation conditions, Al-doped SnO2films are deposited by using the method of RF and direct current (DC) magnetron co-sputtering. The analysis of XRD shows that the crystallinity of SnO2films is improved due to Al doping. With the increase of the Al content, the resistivity of Al-doped SnO2films decreases linearly. Comparing with the undoped SnO2films, the surface grains of Al-doped SnO2films become small and compact due to the doping of Al, and the reflectance and transmittance are enhanced in the visible region, and the strength of the peak the emission spectrum and excitation spectrum films is slightly decreased.Finally, under optimum preparation conditions, Zn-doped SnO2films are prepared by the method of RF and DC magnetron co-sputtering. The crystallinity of Zn-doped SnO2films deposited on Si substrates is increased obviously, and that of Zn-doped SnO2films deposited on glass substrates relatively weak. The resistivity of SnO2films decreases two orders of magnitude with the increase of Zn content, and the lowest resistivity of0.23Ω·cm is obtained. The reflectivity of Zn-doped SnO2films first increases and then decreases with increasing doping power, and increases with the increase of doping time. The maximum transmittance of83.8%is obtained at the doped power of40W. With increasing doping power, the transmittance of Zn-doped SnO2films decreases gradually. Comparing with the undoped SnO2film, the excitation and emission spectra of Zn-doped SnO2films are similar, but the strength is weakened. A red shift of the emission peak of the emission spectra is found, and a blue shift of the excitation peak position of the excitation spectra is found.