INTRINSIC-CARRIER THERMAL RUNAWAY IN SILICON MICROCANTILEVERS

Abstract

A variety of micromachined sensors and actuators use coupled electrical and thermal transport in doped silicon bridges and cantilevers. One example is thermomechanical data storage cantilevers, in which Joule heating and atomic-scale forces yield indentations in an organic substrate. The thermal isolation of these structures augments the temperature rise during Joule heating, which can generate more intrinsic carriers and lead to thermal runaway in the presence of a constant bias voltage. This article develops a simple model for the thermal runaway effect in doped silicon cantilevers. The model relates the electrical conductivity in the cantilever to the temperature-dependent carrier concentrations in silicon and is consistent with the available experimental data.