P-type Zno Thin Films

As aⅡ-Ⅵsemiconductor material, ZnO has a wide direct bandgap (3.3eV at room temperature) and a hexagonal wurtzite structure. ZnO is a unique material that exhibits good performance in optoelectronic,piezoelectric,ferromagnetic and thermoelectricity areas.To develop the application of ZnO-base devices, the first step is to fabricate high quality n-type and p-type ZnO films, and then to prepare transparence p-n homojunction. The high quality n-type ZnO is easily available, while it has been proved that it is very difficult to obtain p-type ZnO due to the self-compensation effect of native defects which was brought during the process of ZnO growing, such as Vo and Zni. Research proves that it is too difficult to prepare good performance p-type ZnO by doping only one element. In recent years, a new way to prepare low resistance and steady p-type ZnO by using donor and acceptor co-doping method have been paid more and more attention.The result of experiment on ZnO research shows that the performance of p-type ZnO was affected by doping element and preparation method. In this study we fabricate p-type ZnO films by Al-N co-doping method and analyse the performance of these films. The main research is as follows:1,ZnO:Al films were prepared by rf magnetron sputtering technique with Al and ZnO as the target and NO and O2 as the source gas, and ZnO:Al:N films were prepared by plasma immersion ion implanted (PIII) method in different dose, realizing p-type ZnO conversion from n-type after high temperature anneal.2,In this study we analyse the effect of crystal structure,electronic and optics performance in different implanted dose. The results of Hall analysis show that only the implanted does of 2.23×1015cm-2 can realize p-type ZnO. The experiment proved that when anneal temperature is 850,area patio of Al 0.6% can gain the best electrics perfoemence, the carrier concentration,Hall mobility and resistivity of the p-type ZnO films are 2.16×1016 cm-3, 32.4 cm2/V·s and 8.90 ?·cm respectively. Through the analysis of result by XRD PL XPS and UV we reach the conclusion that N form N-Al and N-Zn bonds by occupying the O vacancy (VO) and substituting O atoms. Excessive N implanted can arouse new donor defects, cause the performance of p-type to bad condition or even return to n-type.3,Annealing can disassemble Zn(N3)2 which brings by N implanted, so N could substitute O, and this can help to achieve p-type ZnO, and the resistivity can reach the best performance with the rise of the anneal temperature, continue to rise the temperature which would disassemble ZnO and arouse more donor defects, and this can make the performance of p-type ZnO to bad even return to n-type.4,Proper doping Al element could make bond with N, so can accelerate the dissolve of N, and the excessive Al arouse a lot of dornor defects, but because of the dissolve limit of N, it is too difficult to compensate all of these defects. The doping of Al can increase the transmittance of ZnO films in in visible region, after anneal with proper temperature could induce the bandgap to be widened...