Cd_xZn_(1-x)S:SmF_3的红色薄膜电致发光

RED THIN FILM ELECTROLUMINESCENCE OF CdxZn_(1-x)S :SmF_3

本文首次报道了用Cd_xZn_(1-x)S替代ZnS作为基质,改进SmF_3的TFEL的实验;通过适当地在基质中掺杂CdS,在一定程度上提高了SmF_3的TFEL发光亮度;分析了Cd_xZn_(1-x)S基质中Cd含量对SmF_3的TFEL的影响,探讨了发光亮度提高的原因.

It is reported in this paper that CdxZn1-x S has been used to replace ZnS as the host in order to improve SmF3 red thin film electrolu-minesence.According to the PL excitation spectra shown in Fig. 2 , SmF3 exhibits better EL characteristics in CdxZn1-xS than in ZnS crystal . The TFEL panels prepared for the experiment were made with the usual MISIM structure. It is demonstrated in Fig. 3 and Fig. 4 that the luminescence of SmF3 in CdS doped ZnS host shows higher brightness at the same applied voltage than in pure ZnS when the dope concentration is appropriate.Comparison between the simultaneous emission of Er3 + and Sm3 + in the two different hosts has been made to investigate the cause of brightness increase. As Er3+ is considered having approximately the same exciting cross-section, it can be deduced from Fig. 6 that Sm has larger cross-section in CdxZn1-xS than in ZnS. This is probably due to the change of crystal field of Sm3+ luminecence center.However, the Cd concentration in host influences Sm3+ TFEL characteristics not only in increasing the Sm3+ exciting cross-section, but also in causing the drop of the high field in thin film. This is because of the narrower forbidden band and higher mobility of holes and electrons of CdS.The drop of high field will destroy the Sm3+ TFEL when the CdS dope is too high. The best value of x in CdxZn1-x S obtained in our lab is around 0.13.