Temperature-dependent Fowler-Nordheim electron barrier height in SiO2/4H-SiC MOS capacitors

TL;DR

This study investigates the temperature-dependent electrical properties of SiO2/4H-SiC MOS capacitors, revealing a small negative temperature coefficient of the Fowler-Nordheim barrier height, advantageous for high-temperature device operation.

Contribution

It provides the first detailed analysis of the temperature dependence of the Fowler-Nordheim barrier height in deposited SiO2/4H-SiC interfaces, demonstrating improved thermal stability over thermally grown oxides.

Findings

Negative temperature coefficient of barrier height (dFB/dT = -0.98 meV/°C)

Lower temperature dependence compared to thermally grown SiO2

Enhanced high-temperature performance of the MOSFETs

Abstract

This paper reports on the physical and temperature-dependent electrical characterizations of the oxide/semiconductor interface in MOS capacitors with a SiO2 layer deposited on 4H-SiC using dichlorosilane and nitrogen-based vapor precursors. The capacitors, subjected to a standard post deposition annealing process in N2O, exhibited an interface state density Dit = 9.0 x 1011cm-2eV-1 below the conduction band edge. At room temperature, a barrier height (conduction band offset) of 2.8 eV was observed, along with the presence of negative charges in the insulator. The SiO2 insulating properties were evaluated by studying the experimental temperature-dependence of the gate current. In particular, the temperature-dependent electrical measurements showed a negative temperature coefficient of the Fowler-Nordheim electron barrier height (dFB/dT = - 0.98 meV/{\deg}C), which was very close to the expected value for an ideal SiO2/4H-SiC system and much lower compared to the values reported for thermally grown SiO2. This smaller dependence of FB on the temperature and the increase of the current level with temperature in the transcharacteristics measured in the relative fabricated MOSFETs represents a clear advantage of our deposited SiO2 for the operation of MOSFET devices at high temperatures.