Quantitative Characterization of Near-Interface Oxide Traps in 4H-SiC MOS Capacitors by Transient Capacitance Measurements

Abstract

A method to characterize near-interface oxide trap density in SiC MOS capacitors using transient capacitance measurements was investigated, taking account of the distribution of de-trapping time of traps of various locations in oxide. The measurements at room and low temperatures enables us evaluate the responses of the raps of spatially deep and shallow locations, respectively. We found that the sample with low Dit showed smaller density of near-interface traps especially in spatially shallow region in the oxide.

Electron trapping at SiO2/4H-SiC interface probed by transient capacitance measurements and atomic resolution chemical analysis

“…According to Fujino and Kita [17]-that have successfully employed the method on 4H-SiC MOS capacitors-the trapping/detrapping of the NIOTs produces a transient capacitance C(t) (collected in this work from t=0 s and t =600 s) that can be described by extended-Debye relaxation model [22] using the equation:…”

“…Finally, Fujino and Kita [17] presented a method to characterise the NIOTs in MOS capacitors using transient capacitance (C-t) measurements. In particular, the comparison between the measurements at room and low temperatures enabled them to determine the responses of the shallow and deep traps in the oxide.…”

Characterization of SiO2/4H-SiC Interfaces in 4H-SiC MOSFETs: A Review

“…In this context, some authors reported on an anisotropy of the channel mobility µ FE in 4H-SiC MOSFETs, with the channel in different orientations [30,45]. In particular, 4H-SiC MOSFETs fabricated with the channel along the [1-100] direction (along the bunched steps) exhibited a higher channel mobility compared to those fabricated with channel along the [11][12][13][14][15][16][17][18][19][20] direction (across the bunched steps) [45]. Frazzetto et al [29] explained this effect, taking into consideration the impact of both D it and surface roughness in the scattering contributions to the field effect mobility.…”

“…In order to freeze the charged NIOTs, it is preferable to avoid the interruption of the gate bias and to reduce as much as possible the time needed to perform the Vth shift measurement. In the last decade, several time-resolved capacitance-and current-measurements have been employed to investigate the NIOTs [13,14,75]. A faster time resolution provides more information on NIOTs close Figure 11 shows a comparison of different techniques to determine the shift ∆V th in MOSFETs (current measurements) and the flat band voltage shift ∆V FB in MOS capacitors (capacitance measurements).…”

“…The first one is the SiO 2 /4H-SiC interface, which is characterized by the presence of a distribution of interface states (D it ), close either to the valence or conduction band edge [11,12]. Then, a second region inside the gate insulator is characterized by the presence of slow near interface oxide traps (NIOTs) and bulk traps [13,14]. Finally, a "modified" 4H-SiC region close to the interface with SiO 2 is typically present in the MOS system.…”