The crystals of ZnO have the unique combination of semi-conductive, piezoelectric, optical and temperature properties in comparison with the other crystals. These properties provide for successful application of zinc oxide crystals in different fields of science and engineering (piezoelectric converters, optical wave guides, sensors — gas analyzers, opto- and acoustoelectronic devices, scintillators and many others). With good reason ZnO is considered as the most promising semi-conductive system of the new millennium. Generally, the particular application of ZnO, as well as the other semiconductors, is defined by technological opportunities of its synthesis with the appropriate properties. At present time in the world the intensive researches on ZnO are being carried out in the following directions:
- Light-emitting diodes and semi-conductor lasers for UV-area.
ZnO is a semiconductor having the properties similar to GaN. It demonstrates piezoelectric effect, has the forbidden bandwidth of 3,4 eV and exciton binding energy of 60 MeV that is perspective for optoelectronic application.
- Spintronics. Only two wide bandgap semiconductors (GaN and ZnO) are suitable to make spintronics devices at room temperatures.
- Acoustoelectronics. The usage of ZnO single crystals for manufacturing of SAW filters and SAW resonators is rather perspective.
- Touch engineering.
The existence of linear dependence lnR (1/T) in the range of 100-450° C allows using ZnO in temperature sensors, while the dependence of resistance on load and illumination allows applying zincite in pressure sensors and devices of fire alarm system.
- High-temperature devices.
Elastic, dielectric, piezoelectric properties of zinc oxide are differed by the improved stability up to temperature 700 K. The absence of phase transitions and radiation resistance makes this material perspective for application at radiation and high temperatures.
- Automatic systems.
The specific volt-ampere characteristics of zinc oxide can be widely used in manufacturing of automatic systems and electric engineering equipment (varistors, sensors, actuators, automatic switches).
- High-quality crystalline substrates for GaN.
ZnO is alternative to sapphire, as it has not only a proportional crystalline substrate and close factors of thermal expansion, but also meets in the greater degree the requirements to electro-physical parameters.