A. Čerškus

Temperature dependence of the detected voltage of planar microwave diode that operation is based on carrier heating phenomena in strong electric field

Microwave (MW) detectors operating on the basis of charge carrier heating phenomena in semiconductor structures attracts attention of researchers due to the possibility to use such detectors in a wide frequency range. The voltage detected in the devices consists of hot carrier electromotive force arising over the contacts of the structure having n-n+ (or p-p+) junction. Planar design of the microwave diode enabled us to measure the power of electromagnetic radiation from microwaves up to infrared region [1]. The measurements were performed at room temperature, while, the decrease of crystal lattice temperature increases voltage sensitivity of the MW [2]. This increase is caused by an electron mobility and energy relaxation time increase in a high resistivity semiconductor. The sensitivity increase is also influenced by charge carrier density decrease due to their freeze-out at low temperatures. However in a number of applications flat dependence of voltage sensitivity on temperature is preferred. As it is well known, the electron mobility and energy relaxation time depend slightly on temperature in low resistivity semiconductors [3]. Moreover, carrier density in degenerated semiconductors does not depend on temperature. However, carrier heating in degenerated semiconductors encounters phonon assisted difficulties. We have recently demonstrated the ability to detect microwave radiation with planar microwave diode on the base of n-n+ junction with low resistivity n-GaAs at room temperature [4].