The Effect of Self-Heating in LDMOSFET Expansion Regime

In this paper, it is the first time that the effect of self-heating of LDMOS transistors operating in the so-called expansion regime of the output characteristics is studied. Experimental characterization and numerical simulations are used to demonstrate that, in order to explain the origin of the current enhancement phenomenon observed in the output characteristics of LDMOS transistors biased at high gate and drain voltages (which is named as the expansion regime), the thermal effect of the device self-heating, in addition to the proposed intrinsic MOSFET saturation, has to be considered. This is supported by analyzing the temperature, charged carrier velocity, impact ionization rate, and electric field at different positions in the LDMOS transistors biased at different gate and drain voltages.