Microwave heating behaviors of Si substrate materials were investigated in both H and E field The temperature curves could be divided into three stages in H field but two stages in E field according to the changing heating rate With the increase of the Si plate thickness the heating efficiency gradually decreases in both H and E field The boron doping in Si has also an evident influence on the heating behaviors and leads to the reduction of the maximal temperature in the heating curve By contrast a thin Au layer deposited on the Si plate can significantly promote the heating efficiency in H field For all samples although higher microwave power is used for E field heating the maximal temperature of the same sample heated at the E maximum was lower than that at the H maximum confirming that the heating of H field is more effective than that of E field for a high electric conductive sample and reversely E field heating is more superior for a low conductive one (c) 2010 Elsevier B V All rights reserved