氧化锌薄膜光电功能材料研究的关键问题

氧化锌薄膜光电功能材料是近年来新发展起来的研究课题,由于它在短波长光电信息功能材料方面具有潜在的应用前景而备受关注.为了开发ZnO结型光电器件,目前首先需要解决高质量ZnO单晶薄膜的外延及p型掺杂等关键问题.综合国内外的研究结果,结合我们的工作,叙述了利用多晶格匹配原理通过过渡层在Si衬底上异质外延高质量ZnO薄膜,介绍了用SiC作过渡层生长ZnO薄膜的有关问题.对ZnO的p型掺杂,分析了制备p型ZnO的困难和利用Ⅲ-Ⅴ族共掺杂方法生长p型ZnO的作用和优点.

Important Problems of Studying Photo-electronic ZnO Films

Zinc oxide(ZnO)film has been interested by more and more researchers,because of its wide handgap(3.3 eV)and strong exciton binding energy(60 meV).These properties make ZnO have some potential applications in photonics area,such as UV photo-detectors and emitting diodes.In order to fabricate optoelectronic devices,two problems should be resolved.One is the epitaxy of ZnO crystal film,and another one is the p-type doping.This paper mentions the possible methods for epitaxy of ZnO crystal film and p-type doping.We have used Zn buffer layer to improve the quality of ZnO film deposited on Si substrate,according to multi-lattice marched principle.Moreover,we proposed to use SiC buffer layer for depositing ZnO film on Si substrate,because of many advantages possessed by SiC.For p-type doping of ZnO film,there are some difficulties:(a)p-type doping will raise Madelung energy;(b)self-compensation effect prevents national n-type ZnO return to p-type;(c)acceptors have insufficient activation in ZnO films by using p-type impurity alone.The codoping method using group V elements and group Ⅲ elements as codopants may be favorable to solve these difficult,example using N:Ga=2:1.It could increase the incorporation of the acceptors due to the strong attractive interactions between the acceptor and donor dopants.It also could lower the energy levels of the acceptors and raising those of the donors in the bandgap.Then the acceptors can be ionizable easier.