Parameter Extraction Procedure for Vertical SiC Power JFET

Abstract

A practical parameter extraction procedure for a power silicon carbide (SiC) junction field-effect transistor (JFET) is presented. The carrier mobility and carrier concentration are very important parameters, strongly affecting the device current capability and dynamic characteristics for a given design. When modeling JFETs, the values of these parameters are usually based on assumptions and given by a vendor in a range. As a result, model accuracy is compromised. In this paper, a step-by-step parameter extraction procedure is described that includes the extraction of mobility and carrier concentration in the channel and drift regions based on knowledge of device geometrical parameters. For the first time, carrier mobilities in the channel and drift regions of a power JFET are extracted individually. It is found that channel and drift region mobilities can be very different for a given device since they are strongly dependent on the fabrication process. The separate extraction of these two mobilities can also improve model accuracy in the case of imperfect knowledge of the device geometry. The developed procedure includes the extraction of empirical parameters describing the temperature dependence of mobilities in the channel and drift regions. A simple static <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> - <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> characterization and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> - <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> measurements are the only measurements required for the parameter extraction. In this paper, the procedure is experimentally validated for both normally off (enhancement mode) and normally on (depletion mode) JFETs.