Physical properties of Schottky diodes on ZnS single crystals

Abstract

Nearly ideal Schottky diodes are prepared by depositing Au or Al on cleaved ZnS single crystals. The current transport mechanism and barrier height of these diodes are discussed. The agreement of the barrier height values, determined by the temperature dependence of the I–U characteristics, by C–U measurements, and by photoemission investigations is rather good. The current transport is shown to be dominated by thermionic emission. The variation of barrier energy with electric field is reported for Au–ZnS diodes and compared with theory including image‐force lowering. The Schottky barrier photocurrent technique is used for determining the minority carrier diffusion length. The minority carrier diffusion length has values of 4 × 10−5 to 7 × 10−5 cm. In forward bias no electroluminescence is observed unless a high resistive layer due to etching is between the metal electrode and the semiconducting crystal. These nonideal diodes show electroluminescence with forward biases less than 2 V.

Influence of the interfacial layer on the properties of the Au/ZnSe Schottky barrier

“…causes a blue band emission which is more intense and narrow in comparison to the yellow-orange self activated luminescence band. Conceming this last observation and referring to the conclusion presented in a recent paper [29] about the emission properties of ZnS diodes, it can be observed that only Schottky dioded with a thin insulating layer at the interface can rise up an intense forward bias luminescence. From this point of view, it should be interesting to continue investigations of the properties of ZnSe diodes with respect both to the nature and to the thickness of the resistive layer which can be grown accurately controlling its thickness and using free contamination ZnSe surfaces.…”