CW Performances of planar Gunn-effect devices

CW operation of planar Gunn-effect devices was experimentally investigated. The subthreshold potential profile along the active layer was found to redistribute with a time constant of a few hundred microseconds at room temperature, resulting in a high-field layer near the anode. The trigger sensitivity of Schottky-gate devices was also found to be dependent on the trigger rate for frequencies higher than 1 MHz. Electron-trapping effects were confirmed to play an important role in this phenomenon. The device with a "gate notch" in which the active layer thickness is reduced under the gate electrode, was ascertained to be effective in suppressing such anomalous behavior. By performing improvements on the device structure and the circuit construction, the integrated 2-bit shift register was developed. The fabricated circuit was successfully operated at a clock rate of 2.7 GHz under dc bias. Ring-counter operation was also observed by utilizing the present circuit.