The post-damage behavior of a MOS tunnel emitter transistor

The effect of oxide damage on the characteristics of an Al/SiO2/n-Si MOS tunnel emitter transistor, is considered. The pre-breakdown oxide degradation is shown to reduce the current gain and to extend the S-shape segment of the collector characteristic of a device. This kind of damage may be formally modeled as an increase of the SiO2 thickness deviation. After a soft breakdown, the transistor usually loses its bistability and has much lower gain in the range of large currents, while in the low-current mode the device behavior remains almost unchanged. Essential is the size of the zone affected by a breakdown spot, which is, to a great extent, regulated by the conductivity of an inversion layer.