SURFACE CONDUCTION IN CdS.
Abstract
Using four terminal current voltage measurements the authors established that for thin crystals of high resistivity CdS all the dark current flows in a thin layer near the surface. It is estimated that the bulk resistivity is at least 100 times higher than the surface resistivity. This natural sandwich structure (two conduction layers separated by an insulating layer) produces several interesting effects including a self-field effect which causes a strong current saturation similar to that seen but not explained by Bube and Barton. After establishing that a surface conductivity existed, Hall and thermoelectric power measurements were made to determine the transport properties of the surface layer. From these measurements it was not possible to determine whether the surface conduction was due to a bent conduction band caused by nonuniform doping, banding of surface impurities, or banding of intrinsic surface states. Examination of the literature on the chemical properties of crystalline CdS indicated that even at room temperature the surface may react with oxygen especially in the presence of bandgap illumination and moisture. Based on the chemical properties of CdS surfaces a general model is proposed to explain some of the electronic properties of CdS. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1969
- Accession Number
- AD0695823
Entities
People
- Peter Mark
- Roger T. Baker
Organizations
- Princeton University