Computational Simulation Of The Film Depositing Process In Zinc Oxide Using The Reaction Force Field Method

Zinc oxide (ZnO) has recently attracted wide attention of researchers as a new wide band direct gap oxide semiconductor. ZnO has many merits such as, good piezoelectricity properties, gas and pressure sensitivities, inexpensive and abundant raw materials, nontoxicity, good chemical and thermal stability, and strong radioresistance, etc. Therefore, the preparation and control of high quality film become the hot research topics. In order to improve the quality of film, researches requires a thorough understanding of the complex film growth process on the atomic level. The computer simulation just provides such an effective way to study the film growing modes in ZnO in detail and further to reveal the inherent mechanisms of the deposition process.Using the reaction force field method, we theoretically studied the effect of substrate temperature (200K,500K,800K), deposition rate (150m/s,250m/s,350m/s) and the change of oxygen environment (the ratio of O to Zn is10:10,10:9,10:8) on the quality of film. The main results were shown as follows,Series study of the deposition on the ZnO(00l) substrate showed that, when substrate temperature is500K, deposition rate is350m/s, r equals to10:9, the radial distribution function curve of the deposited structure are sharp and highly ordered, the finally formed film possesses the most stable and ordered structure than the other conditions.Series study of the deposition on the ZnO(h00) substrate showed that, it is found that, when the deposition rate is350m/s, substrate temperature is500K, r equals to10:9, the radial distribution function curve of the deposited structure were sharp and highly ordered, the finally formed film possesses the most stable and ordered structure than the other conditions.There are several differences between the deposition on the (00l) and (hOO) substrates. The average total energy and average potential energy increasse along with the temperature of substrate. For the deposition on the (00l) substrate, two growth modes coexisted and the deposited atoms only injected into the top layer of the freedom region; while for the deposition on the (h00) substrate, it appearss one uniform growthing behavior, and the total injected atoms are also much more than the former. To reveal the inherent mechanisms, the effect of the surface energy is further calculated and considered. It is found that, the ZnO(00l) surface is more active than that of the (h00) surface. The later has stronger trend to form the stable compounds with the depositing Zn and O atoms than the former, which can partly explain the film deposting discrepancy between the (00l) and (h00) substrates.