Deep-Level-Transient Spectroscopy Characterization of Mobility-Limiting Traps in SiO&lt;sub&gt;2&lt;/sub&gt;/SiC Interfaces on C-Face 4H-SiC

Hatakeyama, Tatsuko; Shimizu, Tatsuo; Suzuki, Takaya; Nakabayashi, Yukio; Okumura, Hajime; Kimoto, Kôichi

doi:10.4028/www.scientific.net/msf.740-742.477

Cited by 8 publications

(9 citation statements)

References 6 publications

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“…The obtained result is similar to constant-capacitance deep level transient spectroscopy data which has a similar measurement concept. Consequently, the low energy peak may be positioned at 0.16eV [23]. Figure 7.…”

Section: Distributionmentioning

confidence: 96%

Instabilities of SiC MOSFETs during use conditions and following bias temperature stress

Pobegen

Krassnig

2015

2015 IEEE International Reliability Physics Symposium

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We investigate lateral 4H-SiC MOSFETs after switches of the gate bias. We observe a small decrease of the drain current with a logarithmic time dependence which has the same root cause as positive bias temperature instability. The origin of these instabilities is the trapping of electrons into the gate oxide. By varying the device temperature we observe that the charge trapping is consistent with the kinetics of processes with distributed activation energies. The distribution has two distinct peaks where especially the low-energy peak is heavily affected by nitrogen post oxidation annealing.

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Section: Distributionmentioning

confidence: 96%

Instabilities of SiC MOSFETs during use conditions and following bias temperature stress

Pobegen

Krassnig

2015

2015 IEEE International Reliability Physics Symposium

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“…First, we examined the CCDLTS spectra of MOS capacitors on C-face to clarify the cause of the low mobility of the oxynitrided interface [16]. Figure 1 (a) shows the comparison of the CCDLTS spectra between a DWHC sample, the interface of which exhibits a high mobility, and an NHC sample, the interface of which exhibits relatively low mobility.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…The authors reported that the D it close to the conduction band in SiC/SiO 2 interfaces fabricated using oxynitridation was much higher than that of SiC/SiO 2 interfaces fabricated using wet oxidation on C-face by using constant-capacitance deep-level transient spectroscopy (CCDLTS) characterization. [16]. They concluded that the low mobility in SiC/SiO 2 interfaces oxidized in a N 2 O atmosphere on C-face should be caused by trapping electrons in the high density of the traps close to the conduction band.…”

Section: Introductionmentioning

confidence: 99%

“…[15][16][17][18][19] To characterize interface states, we employ constant-capacitance deep-level transient spectroscopy (CCDLTS), which enables us to estimate the energy distribution of the density of interface states close to the conduction band, by utilizing the dependence of the emission time on energy and temperature. [20][21][22] Furthermore, we discuss the effect of the interface states close to the conduction band on electron transport of SiC MOSFETs by simulating the density of trapped electrons, the density of free electrons and the density of total electrons induced by gate voltage at the SiC=SiO 2 interface.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of traps in SiC/SiO₂interfaces close to the conduction band by deep-level transient spectroscopy

Hatakeyama¹,

Sometani²,

Fukuda³

et al. 2015

Jpn. J. Appl. Phys.

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The effects of the oxidation atmosphere and crystal faces on the interface-trap density was examined by using constant-capacitance deep-level transient spectroscopy to clarify the origin of them. By comparing the DLTS spectra of the low-mobility interfaces oxidized in a N 2 O atmosphere with those of the high-mobility interfaces on C-face oxidized in a wet atmosphere, it was found that a high density of traps are commonly observed around the energy of 0.16 eV from the edge of the conduction band (C1 traps) in low-mobility interfaces irrespective of crystal faces. It was also found that the generation and elimination of traps specific to crystal faces: (1) the C1 traps can be eliminated by wet oxidation only on the C-face, and (2) the O2 traps (0.37 eV) can be observed in the SiC/SiO 2 interface only on the Si-face. The generation of O2 traps on the Si-face and the elimination of C1 traps on the C-face by wet oxidation may be caused by the oxidation reaction specific to the crystal faces. * tetsuo-hatakeyama@aist.go.jp 1 I. INTRODUCTION SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) are regarded as promising candidates for the next-generation high-voltage electrical power switches owing to the high critical electric field of SiC [1-3]. However, the low mobility in the SiC/SiO 2 interfaces hinders the potential performance of SiC MOSFETs. Thus, the improvement in the mobility in the SiC/SiO 2 interfaces is a central issue in the research and development of SiC MOSFETs. It was presumed that the traps in the SiC/SiO 2 interfaces are closely related to the degradation in mobility [4]. In 2000, Saks and Agarwal clearly showed that the low mobility in the SiC/SiO 2 interfaces is caused by the trapping of electrons at the highdensity interface traps on the bases of the Hall effect measurements of SiC MOSFETs[5].They showed that most of the inversion electrons induced by the gate voltage were trapped by interface traps by comparing the free carrier density in an interface obtained by Hall measurements with the total number of inversion electrons. They also pointed out that the Coulombic scattering by the trapped electrons may dominate the inversion electron transport by examining the temperature dependence of the Hall mobility. Later, detailed studies on the inversion electron transport of various types of SiC MOSFETs using Hall measurements confirmed the above-described degradation mechanism in mobility [6,7]. Therefore, great efforts have been focused on reducing the interface trap density to improve mobility by examining the gate-oxidation and post-gate-oxidation annealing processes in detail. In recent years, annealing or oxidation in a nitric oxide (NO) or nitrous oxide (N 2 O) atmosphere, which is hereinafter collectively referred to as oxynitridation, has been used to reduce the high density of interface traps [8][9][10]. The optimized oxynitridation process reduces the interface trap density (D it ) evaluated by using the conventional Hi-Lo method [11] down to less than 10 12 cm −2 /eV at E C − E...

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“…This bias adjustment resulted in feedback, which is equivalent to constantcapacitance DLTS (CCDLTS). [14][15][16][17][18] We examined the energy distribution of the interface-state density (D it ) near the conduction-band-edge energy (E c ) in n-type MOS capacitors by the DLTS method. The DLTS method can yield measurements from shallow states to deep states within a single temperature sweep, and enabling us to define the time constant and depth profile of the states.…”

Section: Methodsmentioning

confidence: 99%

Analysis of effect of gate oxidation at SiC MOS interface on threshold-voltage shift using deep-level transient spectroscopy

Hasegawa

Noguchi

Furuhashi

et al. 2015

Jpn. J. Appl. Phys.

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In this study, we investigate the influence of wet oxidation after nitridation of a gate oxide on the interface states in SiC metal-oxide-semiconductor field-effect transistors (MOSFETs). We used deep-level transient spectroscopy (DLTS) to clarify the mechanism behind the positive shift in the threshold voltage after wet oxidation without any significant decrease in the mobility. We applied DLTS using a small pulse to obtain the depth profile of the states. We found that the density of deep-level states near the interface on the SiC side increased after wet oxidation at 600 and 800 °C, whereas the density of shallow states did not increase. This result indicates that the increase in the deep-level states is related to the threshold-voltage shift, and there is no degradation in the mobility.

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Deep-Level-Transient Spectroscopy Characterization of Mobility-Limiting Traps in SiO<sub>2</sub>/SiC Interfaces on C-Face 4H-SiC

Cited by 8 publications

References 6 publications

Instabilities of SiC MOSFETs during use conditions and following bias temperature stress

Instabilities of SiC MOSFETs during use conditions and following bias temperature stress

Characterization of traps in SiC/SiO₂interfaces close to the conduction band by deep-level transient spectroscopy

Analysis of effect of gate oxidation at SiC MOS interface on threshold-voltage shift using deep-level transient spectroscopy

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Deep-Level-Transient Spectroscopy Characterization of Mobility-Limiting Traps in SiO<sub>2</sub>/SiC Interfaces on C-Face 4H-SiC

Cited by 8 publications

References 6 publications

Instabilities of SiC MOSFETs during use conditions and following bias temperature stress

Instabilities of SiC MOSFETs during use conditions and following bias temperature stress

Characterization of traps in SiC/SiO2interfaces close to the conduction band by deep-level transient spectroscopy

Analysis of effect of gate oxidation at SiC MOS interface on threshold-voltage shift using deep-level transient spectroscopy

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Characterization of traps in SiC/SiO₂interfaces close to the conduction band by deep-level transient spectroscopy