Numerical Study of Current Crowding Phenomenon in Complementary 4H-SiC JBS Rectifiers

Abstract

A new type of power semiconductor device -the Junction Barrier Schottky (JBS) diodehas been introduced recently [1]. Our earlier investigations (e.g. [2,3]) on current crowding effect at Schottky interfaces due to barrier height differences created an idea to investigate the temperature influence on current crowding phenomenon in complementary JBS diodes. The reason for such investigations results from the structure (cross section) of JBS diode, which has three different regions for the current flow through the device under upper metal contact. The MEDICI software package for numerical simulations has been used [4].The current distribution along the p-and n-4H-SiC structures under different temperatures, epitaxial layer concentrations and barrier heights (work function) conditions have been investigated and the results are presented. The clear differences in current suppressing behavior around the areas, where the arbitrary pn-junction reaches the upper contact of the structures near the edge of Schottky interface can be seen only in some cases. Our simulations show also the weak sides of the pepilayer SiC JBS, where the temperature influence changes the normal behavior of the device and rearranges the current distribution under higher temperature and barrier height values.

Analysis of Barrier Inhomogeneities of P-Type Al/4H-SiC Schottky Barrier Diodes

“…In Al/ p-type 4H-SiC (DWS# 3) SBD manufactured by DW technology, we can observe that the value of SBH (ΦB0) has ranged from 0.59eV to 1.4eV and a high ideality factor decreasing from 13.9 to 1.8 with increasing temperature. However, Raghunathan et al [34] and another researcher [35,44] recommended that the high value of the ideality factor (n = 2 at ≤ 260°K or more) and low value of the barrier height ((ΦB0)= 0.3 or 0.2) in Al/ p-type 4H-SiC SBD recombination current is dominated at low forward voltage regions instead of classic thermionic emission theory. That might be caused due to electron mobility is lower in fractional ionization of impurities at low temperature for Al/ p-type 4H-SiC SBD.…”