Cd_2SnO_4薄膜光致发光某些性质的研究

STUDIES OF SOME PHOTOLUMINESCENCE PROPERTIES OF Cd_2SnO_4 THIN FILMS

本文研究了Cd_2SnO_4薄膜光致发光的某些性质.Cd_2SnO_4膜是利用Cd-Sn合金靶在Ar+O_2气氛中反应溅射而成的.实验研究表明,Cd_2SnO_4膜的发光峰值随着氧浓度的增加移向长波方向.这是因为氧浓度的增加,减少了膜中的氧空位,导致了导带中电子浓度的减小,致使Burstein-Moss效应和电子散射作用相对减弱,从而改变了带隙宽度.

Cd2SnO4 thin films are a n-type wide-bandgap semiconductor. Thin films of the teinary oxide Cd2SnO4 show the remarkable properties such as low, metal-like electrical resistivity, good transmissivity in the visible range of the light spectrum and high reflectivity in the near IR[1-6]. These films can be used transparent electrodes, heat mirrors and antistatic layers in optoelectronics and solar enrgy conversion technology.In this paper we report the photoluminescence properties of Cd2SnO4 thin films prepared by r.f. reactive sputtering from a Cd-Sn alloy target in an Ar-O2 reactive gas mixture. Experimental results show that the photoluminescence spectrum of Cd2SnO4thin films is very sensitive to the deposition conditions. The photoluminescence peaks exhibit a 'red shift' when oxygen concentration is increased. The variation of emission peaks of Cd2SnO4 thin films may be attributed to the change of oxygen vacancy in Cd2SnO4 thin films. Cd2SnO4 thin films are a n-type defect semiconductor in which oxygen vacancies are believed to provide the donor state [9,10] . The oxygen vacancy concentration can be varied over a wide range with the change of oxygen concentration during deposition. The free carrier concentration of conduction band changes with changing oxygen vacancies. The change of the carrier concentration causes the shift of band gap according to the Burstein-Moss (BM) effect[12,13] and the effect of electron-electron and electron-impurity scattering[14] . Then, the photoluminescence peaks are shifted with the change of band gap.