Optimizing Fabrication Of P Type ZnO Films And Its Applications

ZnO is a new type II-VI group semiconductor with direct wide band-gap. At room temperature, its band-gap is 3.37eV corresponding to the ultraviolet wavelength, and its exciton binding energy is 60meV that is propitious to high efficiency of laser emission. For these properties, ZnO has much potential application in photoelectron field such as LED and LD. But the fabrication of the pn junction based on ZnO is very hard, due to that the undoped ZnO is n type and the fabrication of the p type ZnO is very hard. That has been blocking the application of ZnO in photoelectron field. Many methods have been put forward to solve this problem. At the same time, the pn junctions have also attempted to be fabricated. But either the pn junctions were not successfully obtained, or the pn junction can not achieve the electrical luminance, or the intensities of emission were very low. That's because the poor properties of p type ZnO thin films. So, the fabrication of p type ZnO thin films with high qualities is the key of the application of ZnO in photoelectron field all the same.In this thesis, the p type ZnO thin films were successfully prepared on common glass by Ultrasonic Spray Pyrolysis, through using N-Al co-doped method. The process for preparing p type ZnO thin films was optimized. The p type ZnO thin films were applied in solar cells and pn junctions. The main contents as following:1.The p type ZnO thin films with better properties can be achieved on common glass substrate by adjusting the parameters including the growth temperature and time, the doping ratios and so on. The electrical properties of sample is that the resistivity is 29.6?cm, the Hall mobility is 1.29cm2V-1s-1 and the hole concentration is 1.64×1017cm-3.2.Through inducing the homo-buffer between the common glass substrate and ZnO thin films, the effects of common glass substrates on ZnO thin films were weaken. So the qualities of p type ZnO thin films were improved. The p type ZnO thin films with high hole mobility (12.3 cm2V-1s-1) were achieved.3.Through I-V dual acceptors co-doped new method (selected K and N respectively for I and V elements), the hole mobility of p type ZnO thin films can be increased to14.8 cm2V-1s-1. Because the result is not stable, the more study should be do.4.The p type ZnO thin films were also fabricated on Corning 7059, which were used in microcrystalline silicon solar cells as p type transparent conductive films. The open circuit voltage of the solar cells amounts to 0.47V.5.Both n-Si/p-ZnO and p-Si/n-ZnO hetero-junctions were successfully obtained through growing ZnO thin films on Si wafers directly.6. The homo-junctions based on ZnO were respectively fabricated on various Si wafers, through growing n type ZnO on p type ZnO and growing p type ZnO on n type ZnO.