Abstract
The electrical compensation effect of the nitrogen incorporation at the SiO2/4H-SiC (p-type) interface after thermal treatments in ambient N2O is investigated employing both scanning spreading resistance microscopy (SSRM) and scanning capacitance microscopy (SCM). SSRM measurements on p-type 4H-SiC areas selectively exposed to N2O at 1150 °C showed an increased resistance compared to the unexposed ones; this indicates the incorporation of electrically active nitrogen-related donors, which compensate the p-type doping in the SiC surface region. Cross-sectional SCM measurements on SiO2/4H-SiC metal/oxide/semiconductor (MOS) devices highlighted different active carrier concentration profiles in the first 10 nm underneath the insulator–substrate interface depending on the SiO2/4H-SiC roughness.The electrically active incorporated nitrogen produces both a compensation of the acceptors in the substrate and a reduction of the interface state density (Dit). This result can be correlated with the 4H-SiC surface configuration. In particular, lower Dit values were obtained for a SiO2/SiC interface on faceted SiC than on planar SiC. These effects were explained in terms of the different surface configuration in faceted SiC that enables the simultaneous exposition at the interface of atomic planes with different orientations.
Highlights
The SiO2/4H-SiC interface is the main building block of SiCbased MOSFET devices and its electrostructural quality typically has a direct impact on the device performance in powerelectronics applications
While it is commonly accepted that postoxidation annealings (POA) treatments in ambient NO or N2O have a beneficial effect on the SiO2 insulator and on the SiO2/4H-SiC interface due to the passivation of oxide defects and interface traps by the incorporated nitrogen, the impact of these thermal treatments on the electrical properties of the 4H-SiC substrate is still under debate
Kosugi et al [6] performed X-ray photoelectron spectroscopy (XPS) measurements on 4H-SiC directly exposed to ambient NO at 1200 °C, demonstrating that a significant density of nitrogen atoms (1014 cm−3) is incorporated in the 4H-SiC near surface region and remains even after removing the thin SiO2 layer formed on SiC during the annealing by sustained etching in hydrofluoric acid
Summary
The SiO2/4H-SiC interface is the main building block of SiCbased MOSFET devices and its electrostructural quality typically has a direct impact on the device performance in powerelectronics applications. SSRM measurements were performed on p+-doped (≈1019 cm−3) 4H-SiC areas selectively exposed to ambient N2O (without the presence of the gate oxide to maximize the effect of nitrogen incorporation), revealing a significant increase of the SiC resistivity with respect to unexposed areas, i.e., a compensation effect from the N-related donors.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
