This paper examines the DC power requirements of PIN diodes which, with suitable applied DC bias, have the potential to reflect or to permit transmission of millimetre wave energy through them by the process of inducing a semiconductor plasma layer in the I region. The study is conducted using device level simulation of Sol and bulk PIN diodes and reflection modeling based on the Drude conduction model. We examined five diode lengths (60-140 mu m) and seven diode thicknesses (4-100 mu m) Simulation output for the diodes of varying thicknesses was subsequently used in reflection modelling to assess their performance for 100 GHz operation. It is shown that substantially high DC input power is required in order to induce near total reflection in SOI PIN diodes at 100 GHz. Thinner devices consume less DC power. but reflect less incident radiation for given input power. SOI diodes are shown to have improved carrier confinement compared with bulk diodes (C) 2009 Elsevier Ltd All rights reserved