Study Of Transparent Conductive SnO₂-based And ZnO-based Films

Nowadays,transparent（semi） conductive oxides are of increasing importance in numerous fields, such as displays, clean energy and illumination. For the organic photoelectronic devices, the comprehensive performance（extras including work function, surface topography etc.） became the more practical significance than the traditional criterion, which only includes transparent and conductive. With the development of transparent electronics, we hope the transparent oxide can set enabling high performance TCOs and channel semiconductors for TFTs. In this thesis, we focus on functionalizing non-indium transparent oxides by adjusting the carrier concentration. Our technical means of physics vapour deposition are magnetron sputtering and electron beam evaporation. The detail is as follows:（1） According to the theoretical analysis, the transparent conductive Sn O₂:PrF₃（PFTO） films were designed and prepared by ion-assisted electron beam at a low processing temperature. An optimized PFTO film shows a high average visible optical transmittance of 83.6% and a minimum electrical resistivity of 3.7E-3 ??cm, corresponding to a carrier density of 1.298E+20 cm-3 and Hall mobility of 12.99 cm2/Vs. Amorphous PFTO films show excellent root-mean-square roughness in the range of 1 2 nm, and the commercial FTO films have a higher value of 12.7 nm. The work function of PFTO films was determined to be about 5.1e V, which is much higher than that of FTO（4.4 4.8 e V）. And the PFTO films also have excellent average transmittance in the range of 380 nm to 2500 nm with the value of about 85%. Moreover, the Sn O2:Sr F2（SFTO） films were prepared in the same condition, and the SFTO and PFTO films possess similar optical performance, electrical performance and topography.（2） Through sintering and magnetron sputtering, the novel Y-Ti-V-coped-ZnO（YTVZO） films were developed. The trace V₂O₅ have a great influence on the oxide ceramic. The XRD pattern of the Y-Ti-V-coped-ZnO ceramic is in accordance with that of the hexagonal wurtzite ZnO（JCPDS card No. 36-1451）. And the films achieved optimum growth in the（002） crystal plane. These films deposited in 300℃ show an electrical resistivity of 3.069E-3 ??cm, corresponding to a carrier density of 1.892E+20cm-3 and a Hall mobility of 10.75 cm2/Vs. These films also have excellent average transmittance（> 82%） in the range of 380 nm to 2500 nm. The sheet resistance is stable over 12 months,just rise 1.2%.（3） By adding the carrier suppressor, we succeeded in suppressing the carrier concentration of ZnO films and achieving SrZnO Thin Film Transistor（TFT）. We incorporated Sr into the ZnO semiconductor to suppress the carrier concentration and thereby improve the TFT’s on/off ratio. In addition, the off-state current of the ZnO TFTs is dramatically reduced by three orders of magnitude after adding Sr. Sr ZnO TFT devices display an optimal performance with an on/off ratio of 1E+5, a mobility of 0.05 cm2/Vs, and a threshold voltage of 24.6 V. We also demonstrate the effect of Sr in Sr ZnO semiconductor films on surface morphology. Additionally, the presence of strontium inhibits formation of zinc oxide（ZnO） with the hexagonal wurtzite phase（JCPDS card No. 36-1451） and permits formation of an unusual phase of ZnO（JCPDS card No. 21-1486）.