Photon-Assisted Electron Depopulation of 4H-SiC/SiO2 Interface States in n-channel 4H-SiC Metal-Oxide-Semiconductor Field-Effect Transistors
Sprache des Titels:
Englisch
Original Kurzfassung:
4H-SiC/SiO 2 interface states play a major role in the performance and reliability of modern 4H-SiC metal?oxide?semiconductor field effect
transistors (MOSFETs). To gain new insights into these interface states, we developed a cryogenic measurement technique that uses photon-
assisted electron depopulation to probe device performance limiting 4H-SiC/SiO 2 interface states. This technique enables the characteriza-
tion of shallow as well as deep states at the 4H-SiC/SiO 2 interface of fully processed devices using a cryogenic probe station. Our method is
performed on n-channel 4H-SiC MOSFET test structures with deposited oxide and postoxidation anneal. We identify conditions under
which the electrons remain trapped at 4H-SiC/SiO2 interface states and trigger the controlled photon-assisted electron depopulation within
a range of photon energies. This allows us to prove the presence of near interface traps, which have previously been found in thermally
grown 4H-SiC MOS structures. Our results are supported by device simulations. Additionally, we study the impact of irradiation intensity
and light exposure time on the photon-induced processes.
Forschungs-