NEW COLLECTOR OF PLANAR INSULATED GATE BIPOLAR TRANSISTOR FOR BROAD APPLICATIONS

Abstract

A new concept of Insulated Gate Bipolar Transisitor (IGBT) with a Si/Ge layer collector is proposed to meet different requirements for turn-on voltage and turn-off time. The operation principles of IGBT are discussed and the energy band diagram of Si/Ge heterojunction is employed to explain the inner dynamic mechanism of the proposed IGBT. Two-dimensional (2D) device-circuit mixed-mode simulations indicate that the tail-current, which is a major cause of the power loss and limits the operation speed of the device, is suppressed effectively by using the Si/Ge layer collector. On the other hand, turn-on voltage is increased by the use of the Si/Ge collector. Furthermore, the turn-on voltage is increasing with the increase of the areal rate of the Ge region in the whole collector, while the turn-off time is reversed. This valuable information leads to the freely tunable planar IGBT by adapting the different areal rates of the Ge region to cast to different actual situations. Detailed physical explanations are also given.