Zinc oxide doping level

Zinc oxide is a thoroughly studied typical semiconductor of n-type with the width of forbidden band of 3.2 eV, dielectric constant being 10. Centers responsible for the dope electric conductivity in ZnO are provided by interstitial Zn atoms as well as by oxygen vacancies whose total concentration vary within limits 10 - 10 cm. Electron mobility in monocrystals of ZnO at ambient temperature amounts to 200 cm -s". The depth of donor levels corresponding to interstitial Zn and oxygen vacancies under the bottom of conductivity band is several hundredth of electron volt [18]. 

It is through selecting a proper level of doping zinc oxide wildi elementary zinc that one can completely counterbalance the processes of zinc reduction and fixation on the adsorbent s surface to passivate thus the ZnO film as to the interaction with Hg. The film can be passivated... 

This type of transition has been extensively investigated in ZnS doped with a monovalent d" cation (Cu+, Ag+, Au+) (usually called the activator) and a trivalent ion such as AP+ (coactivator) substituted for divalent zinc. The coactivator can also be Cl substituted for. The monovalent cations create deep acceptor states, Al + or Cl form shallow donor levels (0.1 eV for Al) (Figure 13). When electrons are transferred from the valence to the conduction band, for instance, under electron beam irradiation, they are trapped by the coactivator while holes formed in the valence band are captured by Cu+ or Ag+, which are oxidized to the divalent state. The energy of the photons emitted depends on the energy difference between the donor and acceptor levels and on the acceptor-donor distance ... 

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