可变色的ZnSe:Er3+ MIS发光二极管

本文首次利用高场和低场激发下的有效发光中心,设计和制备了随外加电压极性改变而变色的ZoSe:Er3+ MIS发光二极管。这种发光二极管在正向电压激发下得到蓝色发光,而在反向电压激发下得到绿色发光。

VARIABLE COLOUR ZnSe:Eru3+ MIS DIODES

Implantation of rare-earth ion into ZnSe and ZnS crystals has been used to fabricate light emitting diodes1-4]. ZnS:Er, Nd MS diodes also have been fabricated which give different colours of electroluminescence emission when the efxcitation parameters are changed9]. In this report, the variable colour ZnSe:Er3+ MIS diodes are depicted which are made by means of effective luminescent centers under high5,8] and low7,8] electric field excitation, as shown in Fig.1.ZnSe crystals were grown by sublimation method. The dice with demen-sions of 6×6×1 mm3 were annealed in the molten zinc to reduce their resistivities to the range of l-10Ω·cm. Erbium ions with energy of 100keV and dose of 1×1015cm-2 were implanted into ZnSe substrate at room temperature. Annealing was performed in the molten zinc to eliminate the radiation damage11]. After annealing, an In ohmic contact was made on the substrate. A thick layer (-600Å) of ZnSe was deposited on the implantation surface by evaporation and finally a circular gold electrode (1 mm in diameter) was evaporated on the top of ZnSe layer.Fig.2 shows electroluminescence spectra of the variable colour ZnSe:Er3+ MIS diodes. It is easily found that the diodes give green electroluminescence of Er3+ when reverse biased, and give near band edge emission in blue when forward biased. The luminescent colour is changed with the polarity of applied voltage in this kind of diodes.The luminescent mechanism of the diodes is the high field direct impact excitation when they are reverse biased2-4]. And the blue near band edge luminescence under forward bias could be explained by the hot holes injection10], as shown in Fig.1.