THE INFLUENCE OF CHEMISORPTION ON THE ELECTRONIC PROPERTIES OF THIN SEMICONDUCTORS: OXYGEN CHEMISORPTION ON THE (11-20) SURFACE OF CdS.
PRINCETON UNIV N J DEPT OF ELECTRICAL ENGINEERING
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A theoretical investigation of the effects of chemisorption surface states on the equilibrium conductivity of thin, wide bandgap semiconductors is presented. Criteria are established for the detection and characterization of chemisorption by electrical measurements on the adsorbent. Measurements with oxygen acceptor adsorbate on CdS n-type adsorbent confirm the essentials of the theory 1 There is little or no change in the adsorbent conductivity unless the pressure dependent adsorbate surface state concentration exceeds the adsorbent bulk electron density per unit surface area, and the depth of the surface state below the conduction band exceeds the surface potential necessary to completely deplete the adsorbent bulk. 2 Satisfaction of these conditions produce large changes in the electrical properties of the adsorbent on chemisorption, in both the magnitude of the equilibrium conductivity and in its activation energy. A quantitative study of these effects yields the energy level of the adsorbate and the pressure dependent surface state concentration. Author
- Solid State Physics