Hot-electron emission currents in N-channel IGFET´s

Short-channel effects and the theory of scaling require proportionally increased doping concentrations in the surface channel and/or the bulk substrate regions of Si IGFET´s of short channel lengths. Unless the applied voltages are reduced accordingly, appreciable emission of hot electrons from the Si substrate into the gate SiO2layer may occur. The emission processes can be studied by measuring the gate current directly in the case of channel electron emission, or the optically induced hot-electron emission current in the case of emission of thermally generated leakage electrons. Absolute emission probabilities as well as relative emission characteristics can be determined. These emission characteristics are useful not only for designing Si devices but also for quantitative testing of theoretical models of the emission process. Important physical mechanisms and device parameters in the emission process are discussed.