Hot-electron-induced degradation in MOSFET's at 77 K

Channel hot-electron effects on NMOSFET's operating at liquid nitrogen temperature are investigated for both normal operation and inverse operation where source and drain are interchanged. Following the application of an electrical stress, the threshold voltage is found to increase at low drain voltages and remains unchanged at higher drain voltages; the saturation transconductance remains virtually unchanged during operation in the normal mode. In the inverse mode, the threshold voltage increases irrespective of the drain voltage, while the saturation transconductance decreases. It is noted that hot-electron-induced degradation can be a serious problem in bilateral switching devices.