Quantum modelling of I–V characteristics for 4H–SiC Schottky barrier diodes

Abstract

The prediction of reverse bias I-V characteristics in 4H-SiC Schottky barrier diodes over a wide range of temperatures and bias is not possible using established modelling techniques. This paper reports on the development of an established general model for both reverse and forward characteristics that is applied to 4H-SiC Schottky barrier diodes. This model is based on the self-consistent evaluation of the quantum-mechanical probabilities of carriers to traverse the metal-semiconductor barrier. These are integrated over all possible energies to describe the transport process not only at energies below the barrier but also at energies equal and superior to the barrier height. In this manner the model naturally covers the entire range of the traditional theories of tunnelling, thermionic-field and thermionic emission. The model relies on a single set of parameters, extracted from the experimental forward characteristics of each device using a modified Norde method, to predict both forward and reverse characteristics. The model is compared to measured I-V characteristics, in both forward and reverse bias conditions, for 4H-SiC Schottky barrier diodes fabricated using two different edge termination technologies. Comparisons with models previously described in the literature show a superior fit to experimental data, without the need for additional fitting parameters.

Semi-transparent SiC Schottky diodes for X-ray spectroscopy

“…The ideality factor [17] was below 1.05, which is comparable to those for the thick contact device (1.04 -1.06), indicating a high quality interface between the silicon carbide and the contact. Resistivities under forward conduction are close to 0.03 Ohm.cm 2 which are close to the resistivity of the epi-layer, demonstrating that the Schottky contact is continuous across the full area.…”

“…The reduced barrier height in comparison to a full thickness annealed Ti/Ni barrier is linked to the formation of a titanium rich alloy close to the SiC surface [19]. Whilst this reduction in barrier height increases the leakage current through the diode under reverse bias [17], the increase in practical diodes is lower than expected from theory due to the contributions from other conduction mechanisms including peripheral and surface leakage [20].…”

Combination of thermionic emission and tunneling mechanisms to analyze the leakage current in 4H-SiC Schottky barrier diodes

“…Both models were used separately to analyze the experimental reverse leakage current of SiC and other wide-gap SBDs. Combined and not combined with barrier lowering model, some authors [6][7][8][9][10][11] described the reverse leakage current using the general model [12] of the tunneling current. At the same time, the others [13][14][15][16][17][18] used the thermionic field emission (TFE) developed by Padovani-Stratton [19] also with and without the effect of the image force barrier lowering.…”

A Compact Model for SiC Schottky Barrier Diodes Based on the Fundamental Current Mechanisms

“…To simplify the problem, we will take the standard deviation to be X 1 kT, where X 1 is a numerical parameter which will later be optimized for a given device. Doing this gives (4). This parameter represents a weighted average standard deviation for the field emission current component across the operation range.…”