Basic Properties of Zinc Oxide

The above discussion of the band model and its application to a description of equilibrium chemisorption has been brief and incomplete. It is not the principal purpose in this paper to discuss surface barrier effects in equilibrium chemisorption, but rather surface barrier effects in the irreversible region of chemisorption. However, before we begin the consideration of these latter effects, we will digress and examine the basic properties of zinc oxide, which material will be used both as motivation and as illustration in the following text. 

Zinc oxide seems to be a semiconductor with many of the properties necessary for a comparison with the electron transfer theory partially described in the preceding chapter. 

The material has been found to be an W-type semiconductor at all temperatures (24-27). The donor impurities, as has been quite well established (24,28), are interstitial excess zinc atoms. Their concentration depends on the method of preparation of the sample, ranging from 10 cm.- to 10 cm.- (24,28). 

Of the various types of surface states available, evidence will be presented below which indicates that the only deep surface traps are adsorption traps. The possibility exists that some very shallow surface 

As will be discussed later in this section, most of the investigations on zinc oxide have been done on specimens whose structure allows the surface effects to be large. 

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