Preparation And Research Of P-type Conductive Transparent Tin Films And PN Junction

Transparent conductive oxide (TCO) films are widely applied in various optoelectronic devices, such as solar cells, thermoelectric materials and transparent electrodes, due to the characteristics of transparency in the visible region and low resistivity. Due to the high ultraviolet absorption coefficient and visible light transmittance, resistance of alkalinity or acidity at room temperature and chemical stability, tin dioxide (SnO2) film became one of the most widely applied TCO films. At present, TCO films in application are mostly n-type conductive, p-type conductive TCO films matching with the corresponding n-type films can be prepared a transparent pn-junction, that will be a significant progress in the field of electronic components.According to the theory of semiconductor physics, the shallow level doping of the main elements can provide the p-type conductive properties of the oxide film. Base on this theory, summarize and improve the reported results,we study the preparation of p-type conductive SnO2:Sb (ATO) films using magnetron sputtering method of doping shallow level element Sb by sputtering different types of target. By controling the sputtering process conditions and annealing treatment for the deposited ATO films, make Sb take the Sn atomic positions in the SnO2lattice of effectively, forming the acceptor doping, so that make the ATO films have p-type conductivity. By DC reactive magnetron sputtering the Sn/Sb alloy-target, oxygen flow rate less than8sccm, substrate temperature200~250℃to fabricate p-type conductive ATO film; When the oxygen flow keeps at4sccm, substrate temperature at200℃, the hole-concentration of p-type ATO films reaches4.223x1019cm-3, the conductivity reachs0.3973S·cm-1. Using RF magnetron sputtering ceramic target are more likely to get good crystallization, uniform components, dense structure p-type ATO films than DC reactive magnetron sputtering, the annealing treatment temperature is very important for the conductivr properties of the films. The deposited ATO films annealed at650℃in argon atmosphere for4hours has the best p-type conductivity compared with other p-type TCO films reported before, the hole-carriers concentration is1-2orders of magnitude higher than the reported, reachs1.722x1020cm-3, the conductivity is60.61S·cm-1, the average visible transmittance is more than80%. Through the analysis, we find that annealing treatment affects acceptor doping efficiency and crystal structure of the ATO films, than influence the p-type conductive properties. Crystal good components uniform, structure, the formation of the p type conductive ATO film, heat treatment temperature on the electric properties of the film is very important.In addition, based on the the excellent performance of p-type conductive ATO film and matching n-type conductive ZnO:A1(AZO) film, we fabricate the transparent heterogeneous pn-junction. It has good rectifier characteristics, open-circuit voltage7.40V, and no reverse leakage current.