Investigation of performance limiting point defects in SiC MOSFETs using electrically detected magnetic resonance
Gernot Gruber
Institute of Solid State Physics, TU Graz; KAI GmbH
http://www.k-ai.at
15:20 - 17:30 Thursday 24 October 2013 Foyer Alte Technik Silicon carbide (SiC) is a promising semiconducting material for power applications. Its material properties are superior to silicon. In particular, SiC has a larger band gap, a higher breakdown field, and a higher thermal conductivity [1]. However, material processing is more challenging since SiC is a compound material. For metal oxide semiconductor field effect transistors (MOSFETs) a good interface between the semiconductor and the oxide is crucial for device performance. The conducting channel of an operating transistor forms at this interface. If electrically active defects are present, the charge carriers are disturbed which leads to a decrease in the mobility and a higher channel resistance. In order to improve the devices and obtain a high mobility it is desired to gain more knowledge of the interface defects.
One of the few methods that can be applied is electrically detected magnetic resonance (EDMR). It is a combination of electron spin resonance (ESR) which provides structural information, and electrical measurements which are very sensitive. The unpaired electrons of paramagnetic defects split their states when a magnetic field is applied, which is known as the Zeeman Effect. In an ESR experiment an oscillating field, conventionally in the microwave regime, is used to induce resonant transitions between the different states and spectroscopic information of the defect can be gained. EDMR takes advantage of the fact that under resonance also parameters like the carrier recombination rates through the defect may change which can be measured as a current change. It is possible to measure the atomic structure of the defects that limit the device performance in a fully processed device with high resolution and within a small area of the device [2, 3]. Therefore, EDMR is a powerful tool to assist the development of SiC MOSFETs and offers the possibility to answer open questions.
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