Adsorption and desorption behavior of CO on S passivated 4H-SiC by elec

Abstract

Adsorption energy and partial density of states of S at three typical positions on 4H-SiC (001) surface were calculated which based on the density functional theory (DFT).The results show that S adsorption is the most stable in the bridge position and unstable in the hollow. The density of states near the Fermi level can be effectively reduced by using the S atom on the surface of 4H-SiC. The adsorption and desorption of CO on the surface of S passivated 4H-SiC at different applied electric fields were calculated by selecting hollow of S atom adsorption. It turned out that the positive electric field is not conducive to the adsorption of CO and the reverse is favorable for adsorption, but when the forward electric field F is greater than 2eV/Å/e the desorption behavior of S atom is more obvious. Because of the S atom is positively charged which made the Si-C bond length increases rapidly under the action of electric field.

Source:IOPscience

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Evaluation of nitrogen incorporation into bulk 4H-SiC grown on seeds of different orientation from optical absorption spectra

The effectiveness of n-type nitrogen doping of bulk 4H-SiC grown on seeds of different orientation is studied by optical absorption measurements. The 4H-SiC ingots have been grown by physical vapour transport (PVT), with nitrogen doping from the SiC source. The nitrogen concentration was determined at room temperature from the absorption peak intensity at 464 nm, with account for the degree of donor ionization. It has been shown that 4H-SiC ingots grown on Si (11-22) faces are significantly less doped by nitrogen than the ones grown on C (11-2-2).

soource:Iopscience

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The defects regulating for the electronic structure and optical properties of 4H-SiC with (0001) surface

Highlights

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The pristine (0001) surface and surface with defect structures for 4H-SiC are proposed.

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The regulating mechanism for electronic structure of 4H-SiC relies on the electron distribution on the surface.

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Electron-transfer and optical properties of 4H-SiC (0001) surface should be controlled by the defect types.

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The formation energy of defect surface is calculated and it is a judgement standard of defects surface stability.

Abstract

The electronic structure and optical properties of 4H-SiC bulk, pristine (0001) surface and the (0001) surface with defects have been studied by the first principles plane wave method. The results showed that 4H-SiC is an indirect semiconductor with the band gap of 2.045 eV, the pristine (0001) surface was an indirect n type semiconductor with the band gap of 0.65 eV, the (0001) surface with defect of carbon vacancy (VC) was an indirect p type semiconductor with the band gap of 0.46 eV, the (0001) surface with substitution Si for C (SiC) was a semimetal. The optical properties of 4H-SiC were modulated by the electronic bonding types of Si 3p and C 2p. The calculation provided theoretical reference for the study of 4H-SiC.

Keywords

4H-SiC,Formation energy,Electronic structure,Optical properties,First principles

Source:ScenceDirect

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Angle-resolved photoelectron spectroscopy study of initial stage of thermal oxidation on 4H-SiC(0001)

Abstract

A key to improving the performance of SiC MOSFETs is to clarify the SiO2/SiC interface structure formed by thermal oxidation. We have investigated the initial stage of thermal oxidation on 4H-SiC(0001) by angle-resolved photoelectron spectroscopy. From the changes in the Si 2p3/2 and C 1s photoelectron spectra, the changes in the chemical bonding state of the SiO2/SiC structure with the progress of thermal oxidation were observed. We also found that the intensity of C–O bonds in the case of 4H-SiC(0001) was smaller than that in the case of 4H-SiC() with the same oxide thickness and that the oxidation rate of 4H-SiC(0001) is already slower than that of 4H-SiC() in the early stage of oxidation.

Source:Iopscience

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Recent advances in 4H-SiC epitaxy for high-voltage power devices

Abstract

This paper reports recent advances in high-quality 4H-SiC epitaxial growth. The modern 4H-SiC epitaxial reactors, techniques to improve growth rates and large-diameter uniformity and reduce defect densities are discussed. A single-wafer vertical-type epitaxial reactor is newly developed and employed to grow 150 mm-diameter 4H-SiC epilayers. Using the reactor, high-speed wafer rotation is confirmed effective, both for enhancing growth rates and improving thickness and doping uniformities. Current levels of reducing particle-induced defects, in-grown stacking faults and basal plane dislocations and controlling carrier lifetimes are also reviewed.

Keywords

4H-SiC;

Power device;

Epitaxial growth;

Dislocation;

Stacking fault;

Carrier lifetime

Source:ScienceDirect

If you need more information about SiC 4H,please visit our website:www.qualitymaterial.net,and send us email at angle.ye@powerwaywafer.com or powerwaymaterial@gmail.com.