Simulation of SiC High Power Devices

Abstract

The impact of SiC on high power devices and their applications is analysed using simulations in a very wide range of design voltages. First, a detailed presentation of the anisotropic form of the basic equations and of the physical models for 4H‐SiC used in the simulations is given. Following that the application ranges of unipolar and bipolar devices in the domains of voltage and frequency are predicted in the case of IGBTs versus MOSFETs and PiN versus Schottky rectifiers based on comparisons of the on‐state voltage and of the total losses. The application limit of the MOSFETs compared to IGBTs and of the Schottky rectifiers compared to PiN rectifiers is predicted to be about 4.5 and 2.5 kV, respectively, in the case of the 4H‐SiC polytype. The impact of technological limitations of SiC is illustrated by the case of low channel mobility. The merits of SiC as compared to Si are illustrated by the case of a SiC rectifier operating together with a Si IGBT. Dramatically reduced turn‐on losses are demonstrated. The superiority of SiC from the point of view of dynamic avalanche is predicted and illustrated. Finally, some novel SiC switch structures are introduced in response to the reliability problems encountered in ordinary trench MOSFETs.

Forward current-voltage characteristics simulation of 4H-SiC silicon carbide Schottky diode for power electronics

“…In particular, we assumed that and mobility and diffusion coefficients can be described by Einstein's equations. Finally the system of the basic equations for simulation model of Schottky diode must be given by expressions of the form [2], [5]:…”

“…In the presented model also were included Shockley-Read-Hall model recombination, Auger recombination and anisotropic impact ionization [5]. Boundary conditions between Ni metal contacts for 4H-SiC layer on a lateral surface of the cylinder were used as standard for Schottky diode [2], [5].…”

“…Where Io is the saturation current and n the ideality coefficient [5]. In this case if plots the dependence of ln(Io/T 2 ) on 1/(nkBT) (the Richardson plot) it is possible to obtain the effective barrier height for Schottky diode [2], [6].…”

Influence of the anisotropy on the performance of D-band SiC IMPATT diodes

“…The low-field mobility model used in the simulation is given by [30][31][32] l n;p ¼ l n;p;min T 300 a n;p þ l n;p;max…”

“…The electron and hole majority carrier mobility as functions of temperature, doping and directions in epitaxially grown 4H-SiC material has been experimentally given, and it is found from their measurements that the electron mobility of the \11 " 20[ direction for 4H-SiC is 0.83 times of that of the \0001[ direction above 200 K [30,32], as listed in Table 3. Meanwhile, the widely used parallel field mobility (FLDMOB) model is employed for 4H-SiC high-field mobility in this simulation, which can be described as…”