Critical electric field for transition of thermionic field emission/field emission transport in heavily doped SiC Schottky barrier diodes

In this study, n-type SiC Schottky barrier diodes (SBDs) with various doping concentrations (⁠$Nd=4×1015$–$1×1019cm−3$⁠) were fabricated, and their forward and reverse current–voltage (I–V) characteristics were analyzed focusing on tunneling current. Numerical calculation with the fundamental formula of tunneling current gives good agreement with experimental forward and reverse I–V curves in the heavily doped SiC SBDs (⁠$Nd>2×1017cm−3$⁠). The analysis of the energy where electron tunneling most frequently occurs revealed that field emission (FE) tunneling dominates conduction instead of thermionic field emission (TFE) under a higher electric field in reverse-biased heavily doped SiC SBDs, while forward I–V characteristics are described only by TFE. In addition, the critical electric field for the TFE–FE transition is quantitatively clarified by carefully considering the sharply changing electric field distribution in SiC with a high donor concentration.