Sensing and measurement with self-sustained acoustoelectric and photoelectric oscillations in structures with relaxation

The new possibilities of self-sustained oscillations of acoustoelectric and photoelectric voltages accompanied by surface acoustic wave and light self-modulations in layered semiconductor-piezoelectric and metal-dielectric-semiconductor structures with relaxation that we have discovered are presented with a view of sensing of physical and chemical environmental parameters and measurement of semiconductor electronic parameters. It gives principal methods to improve sensitivity and precision because the frequency of the self-sustained oscillation or self-modulation /spl Omega/ is expressed in terms of the charge-discharge relaxation time /spl tausub s/ of the metal-piezoelectric-semiconductor or metal-dielectric-semiconductor structures. The frequency of self -sustained oscillations /spl Omega/ allows relaxation time /spl tausub s/ to be determined directly. This connection between /spl Omega/ and /spl tausub s/ can successfully be used in physical and chemical sensors with frequency output and may be a basis investigations of semiconductor parameters such as surface states' parameters and their spectroscopy properties. It is the great interest because of in the precise sensors and investigation methods we use self-organization processes in which the frequency of electrical signal can be easily measured with high precision and it gives high sensitivity.<>