Study On Electronic Structure Of Crystal Film

Since exciton was put forward, the studies in the experiment and theory about it had been lasted for 40 years, the experimental equipment for studying exciton in the semiconductor is simple and the process is mainly taken by optical ways, for the sake of the high temperature of the sample during the process, so the cost is low. Because of the anisotropy of the electron and hole's effective mass in the solid, which makes it very complex to handle the many body system of exciton in the theory, even many results are still concluded qualitively. The studies can be divided two steps, the focuses are mainly on the exciton in bulk materials before 1980s.After 1980s, the more unique properties in the low dimensional materials are reported, the studies about excition was introduced into low dimensional semiconductor field by a paper of G. Bastard. Later, a series studies about exciton in low dimensional scale were taken, the energy level and binding energy in several conditions such as quantum dot,quantum wire,quantum well are studied and many ways were developed. Until now, exciton in low dimensional systems are still a focused filed. This paper can be divided into three parts, the first part is mainly discussed in this paper from first section to third section, the general equation about exciton is constructed and the spectrum of exciton of the simple cubic crystal are studied in the first part, later, two different perturbation to exciton's energy level are discussed. It is noted that this paper is studied theoretically, the parameters are chosen randomly and no unique material has these parameters; the exciton's energy of ground state and the first excited state of ZnO are discussed in the second part including forth section, because ZnO is not scc but wurtzite cystal and dispersive relation of energy can not be written directly like scc, so we take the rather simple effective mass variable method to discuss the energy of groud state, the levels of lowest energy can be discussed by this method and the error increase as the energy increase; The third part include sixth section, Because the energy dispersive relation are not written analytically in the second part, the valence wavefucntions and band structure are calculated by the k . p perturbation method and the effective mass approximate method in third part.The energy of exciton and the binding energy of exciton can be discussed base on calculation of the energy band structure in ZnO film, and DOS and the population of charge carrier can be calculated further, which can guide the design of the ZnO photoelectron and laser devices.