Temperature dependence of substrate currents of MOSFETs under different drain and gate biases

In this study, the problem of substrate currents of metal-oxide- semiconductor field-effect transistors exhibiting different temperature dependence at different gate and drain voltages is investigated. The unsolved so-called 'transition point' problem is found to be ascribable to the different sensitivities of thermal kinetic energy and phonon scattering effects to the variation of drain voltages. To include the influence of temperature and gate voltage, a new mathematical model for substrate current is proposed, which also reveals that modeling using the lucky electron approach cannot obtain satisfactory accuracy and that the transverse electrical field from gate bias is not a negligible factor. With the evidence from experiments, this article also points out that using the substrate current to monitor the severity of the hot-carrier effect is not reliable when the drain voltage is lower than the transition point.