Observation of hot-hole injection in NMOS transistors using a modified floating-gate technique

A modified floating-gate technique for measuring small gate currents in MOSFET's with very high resolution (0.01 fA) is described. Using this technique, gate oxide currents due to hot-carrier injection are measured in n-channel MOSFET's. The conventional negative channel hot-electron gate oxide current is observed nearVg = Vdand a small positive gate current occurs at low Vg. We argue that the dependencies of this small positive current on Vgand gate length, together with results from a separate floating-source experiment, are consistent only with hot-hole injection.