Over the past twenty years, significant progress has been made in improving the technology of fabricating thin films based on metal oxides, and this progress has made it possible to obtain epitaxial ZnO thin films that retain some of its inherent attractive properties 4, 5. Unlike these compounds, ZnO is a common material with non-toxic and biocompatible properties. Similar properties have some compounds of A III – B V groups, for example: GaN or GaAs, which are successfully used in optoelectronics or in microwave integrated circuits 1- 3. Zinc oxide is a transparent, wide bandgap semiconductor with many interesting properties. Additional traps due to surface states form a depletion region with screening of spontaneous polarization, which can be used as a channel in a ZnO:Li/ZnO:Ga or ZiO:Li/Ag FET. These factors lead to band bending and limitation of charge carrier mobility. In particular, it has been shown in ZnO:Ga/ZnO:Li two-layer systems that the interboundary charge is due to two factors: the first factor is the difference between the Fermi levels and conductivities of the ZnO:Ga and ZnO:Li films, the second factor is the presence of polarization in the ZnO:Li films and the absence of polarization in the ZnO:Ga film. The compensation process leads to the bending of the conduction bands and the appearance of localized states 10.
Spontaneous polarization, as in traditional ferroelectrics, is compensated 8, 9. One of these properties is associated with the presence of spontaneous polarization: when 10% Li is added, the film acquires ferroelectric properties with spontaneous polarization PS in the direction of the crystallographic C axis 6, 7. Similar properties have some compounds of A III - B V groups, for example: GaN or GaAs, which are successfully used in optoelectronics or in microwave integrated circuits 1- 3.
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