Gunn effect digital devices are considered to be representative functional devices which can solve the problem about the drastic increase of device number, i.e. so called numeric barrier to meet the demand for modern high speed information processing systems.
This paper views the development of the Gunn devices which can achieve this from the basic elements and describes two kinds of sub-system constructions.
Many problems to be solved which are concerned with the stable operation and reliability, still remain in order to put them into practical use. However, the Gunn effect functional device is considered to have many promises in the future.