Ultrashallow defect states at SiO2∕4H–SiC interfaces

Abstract

Interface state density (Dit) at SiO2∕4H–SiC interfaces are reported for states lying energetically within ∼0.05–0.2eV of the conduction band edge (EC) of 4H–SiC using capacitance-voltage characterization as a function of temperature. Comparison of as-grown dry oxidized and nitrided interfaces confirms the significant reduction of Dit associated with nitridation. In the as-oxidized case (no nitridation), the Dit in the energy range ∼0.05–0.2eV below EC is found to consist of a broad Dit peak at about ∼0.1eV below EC with an energy width of about ∼0.2eV and a peak magnitude of ∼2×1013cm−2eV−1 superimposed on an exponentially decaying background distribution. Interfacial nitridation completely eliminates the broad peak but does not strongly affect the background.

A new 4H-SiC hydrogen sensor with oxide ramp termination

“…4(a). The interface state distribution is highest near the 4H-SiC conductionband edge, where D it values rapidly increased, approaching values greater than 10 13 cm À 2 eV À 1 , similar to previously reported studies [36][37]. It can be observed that there is a difference between the shallower and the deeper states below the conduction band, the magnitude of D it at levels deeper than 0.2 eV being relatively low for the thickness of the oxide used and no additional postoxidation treatment.…”

Growth and surface analysis of SiO2 on 4H-SiC for MOS devices

“…In general, it is higher at both ends of the conduction and valence bands than that at mid-gap of semiconductor [49,50]. The density of interface traps at band edge of our samples is higher than the reported value of 10 13 -10 12 cm −2 eV −1 [51]. The negative sign of D it of the samples consistently supports occurrence of positive interface traps at the interface.…”

N-channel field-effect mobility inversely proportional to the interface state density at the conduction band edges of SiO2/4H-SiC interfaces

“…19,23 The calculated DOS is plotted in Fig. 6(b), and is shown to be significantly less than D IT near E C .…”

“…While Eq. (4) is based on the Gray-Brown method, 18,19 we apply the method to MOSFETs rather than to MOS capacitors because of a drawback encountered when using MOS capacitors. For MOS capacitors, the lower temperature limit is restricted by the freeze-out of the nitrogen donor.…”

“…[1][2][3][4][5][6][7][8][9][10] Although the interface states have been assumed to be a main cause of the low channel current, 2,3,6,7,10,16 a clear correlation between the interface state density (D IT ) and the channel performance has not been determined. 11 We recently showed that the peak n-channel field-effect mobility (µ FE,peak ) at room temperature is roughly inversely proportional to D IT for samples on the (0001), (000-1), and (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) faces (the Si-, C-, and a-faces, respectively) after dry/nitridation and pyrogenic/hydrotreatment processes, 12 where D IT was evaluated by the C−ψ S method 13 at 0.2 eV below the conduction band edge (E C −E T = 0.2 eV) using MOS capacitors. However, µ FE,peak for a-face MOSFETs is higher than those for the Si-and C-face MOSFETs at the same D IT .…”