Zno: Research On Electrical Property Of Zns Thin Film And Its Heterojunction Administered Ultraviolet Light

ZnO as a third-generation semiconductor material, due to its wide band gap, low cost, easy preparation, it has a very widely used in photonics applications, such as LEDs, laser diodes and UV detectors. Though UV detection has made a series of achievements, its inherent defect which leads to slow photoresponse is still a problem. In order to achieve a better application of ZnO in optoelectronic devices, the conductance characteristics and bandgap engineering of ZnO should be study, which involves n-type or p-type doping of ZnO and band adjustment.In order to make better use of ZnO, Mg and transition elements doping have been extensively studied. However, less attention has been paid to anion doping, especially chalcogen elements in ZnO. S doping in a ZnO system is expected to show electrical and optical properties because of large electronegativity and size differences between S and O. In addition, the band gap (Eg) engineering might be possible because of larger Eg of ZnS than ZnO. The stable structure of ZnS is wurtzite structure. ZnS is a direct band gap semiconductor material which has a wide bandgap and a strong UV absorption edge.The difference of lattice constant between ZnS and ZnO is very small, and the energy band structure of ZnS meets.the requirements of heterojunction formation with ZnO. Based on the above two points, high-quality ZnS films may epitaxial grow up on ZnO thin film and form a good heterojunction with ZnO film. Therefore, doping and the formation of the heterojunction to improve the electrical properties of ZnO is a very meaningful job.The main content of the paper include the following aspects:(1) Relevant knowledge of ZnO was summarized to introduce the structure and basic properties of ZnO. This paper mainly pays attention to the research progress, basic properties, band structure, morphology and defects.(2) In order to calculate and analyze the energy band structure,density of states, the formation energy and the doping impurities concentrations of ZnO and the S-doped ZnO system, the castep model of Material Studio5.5was used to calculated. So that we can theoretically verify how S-doped in ZnO affect the optical and electrical properties of ZnO.(3) S-doped ZnO thin films were fabricated by magnetron sputtering equipment and the photoelectric characteristic was analyzed.This paper mainly focused on the UV conductance properties of the films. The results show that under a certain amount of S-doped concentration, the films have good photoconductivity and carrier concentration is about three orders of magnitude higher than intrinsic ZnO films.(4) Through literature review, the structure of ZnO/ZnS heterojunction was demonstrated. A ZnO/ZnS heterojunction was fabricated by magnetron sputtering equipment. The results show that the structure has switching properties, but the turn-on voltage is smaller less than2V. The UV-response characteristics significantly show this structure has potential applications.