A comprehensive study of inversion current in MOS tunneling diodes

The gate current of MOS tunneling diodes biased at inversion region with different substrate doping is investigated. For p-type substrate (1-5 Ω-cm) devices, the tunneling diode works in the deep depletion region and the inversion current is dominated by the thermal generation rate of minority electrons via traps at Si/SiO ₂ interface and in the deep depletion region. The activation energy is approximately equal to half of the silicon bandgap independent of gate voltage. For devices on p ⁺ substrate (0.01-0.05 Ω-cm), the band-to-traps tunneling and band-to-band tunneling are the dominating current components at inversion bias, and reveal a strong field dependence and a weak temperature dependence. The band-to-traps and band-to-band current components are even more significant in the devices on the p ⁺⁺ substrate (0.001-0.0025 Ω-cm). Finally, the effects of temperature and light illumination on inversion current of MOS tunneling diodes will be also discussed.