A First Principle Study On The Structure And Performance Of ZnO Type Thin Film

Zinc oxide (ZnO) is compound semiconductor of Ⅱ-Ⅵ with a series of merits, suchas wide direct, high exciton binding energy, innocuity, low cost, high radiation protectionand so on. So, ZnO is considered to be a new kind of photo-electric semiconductormaterial which has a broad application field and is a hotspot of study recently. In thispaper, we perform first-principle calculation which is based on density functional theory(DFT) to investigate the related performance of ZnO and its doped system. Besides, theatomic structures and optical properties of ZnO:Al under the strain have also been studied.The inner physical mechanism is sought by comparison and analysis.Firstly, the doping way of replacing Zn is adopted to investigate the ZnO system withdifferent Al content. The result show that the lattice parameters increased with the Alcontent, and the ability of conductivity continues to increase. The physical mechanism ofband gap increment is also discussed in detail. Besides, we find that when the dopingcontent is bellow25%, the blue shift of the optical absorption edge is observed and redshift happed when the Al content is25%, in addition, it has the high infrared reflected.Secondly, research and discuss the structure and electricity performance of ZnOdoping after Ga, and with the same conditions of doped ZnO: Al, do a comparative study.The result show that the wurtzite structure of ZnO didn't change after doping Ga, and theamplify range (2.6%) is larger than the ZnO doping with Al. The thermostability ofZnO:Al is higher than the ZnO:Ga, but the conductivity of ZnO:Ga exceeds the ZnO:Al.Explain the physical mechanism through the analysis of the state density.Finally, we perform the setting method of the hydrostatic pressure in CASTEP todiscuss the structure ZnO:Al under different pressure based the primary principlecalculation. The affect on electronic structures and optical properties was calculated andanalyzed. With the increase of stress on ZnO:Al, the results showed that volume ofZnO:Al became small, and the conduction band and valence band both broaden and therange increased with the pressure linearly. Besides, the Absorption peaks move to highenergy level and the system of ZnO:Al still keeps high transmission of light.