We have investigated and reported the results on oxidized-SiN gate oxides on n-type 4H-SiC. The quality of this oxide has been compared with thermal nitrided and dry oxides. In the oxidized-SiC sample, a significant improvement in oxide deposition/growth rate has been obtained while the metal-oxide-semiconductor characteristics of the oxide are comparable to the thermal-nitrided oxide and much better than dry oxide. This achievement has been explained using a proposed chemical model.The excellent physical and electrical properties demonstrated in 4H-SiC have promoted this material to be used as a substrate for high temperature, power, and frequency electronic devices. 1-3 Compared with other wide bandgap materials, SiC has the ability to form native oxide by thermal oxidation. This has promoted the development of a SiC-based power metal-oxide-semiconductor field effect transistor ͑MOSFET͒. However, SiC-based MOSFETs have not been realized for practical use for two main reasons. One is the difficulty to thermally oxidize SiC due to anisotropy of the material, 4 and the other is the high density of SiO 2 /SiC interface traps. The prevailing factor contributing to the high interface-trap density ͑D it ͒ is the existence of intrinsic carbon that originated from two sources, residual carbon from surface of substrate prior to oxidation and carbon generated at the interface during oxidation. 4,5 In order to solve this problem, thermal nitridation ͑as explained by the nitridation model 6 ͒ has been proven as the best technique to grow a device-grade gate oxide. By using thermal-nitrided oxide, a significant reduction in SiO 2 /SiC interface traps, increment in MOSFETs channel mobility, reduction in leakage current, and improvement in gate oxide reliability has been reported. 6-8 This type of oxide can be grown on SiC by direct thermal nitridation or postgrowth thermal annealing in NO or diluted N 2 O ambient. 6-8 However, using these techniques, the oxide growth rate is extremely low and it is difficult to obtain thick oxide with high quality. 9 It is important to develop a technique that is able to grow/deposit an oxide with good quality in a decent time frame. Therefore, in this article, a relatively fast thin nitrided-oxide growing/depositing technique with comparable oxide quality to its thermal-nitridation counterpart has been investigated and reported. In this technique, a required SiN thickness is deposited on 4H-SiC using a remote plasma-enhanced chemical vapor deposition ͑PECVD͒ system. After the deposition, the sample is oxidized in dry oxygen ambient. The MOS characteristics of this oxide have been reported here.n-Type, 8°off ͑0001͒ oriented, 4H-SiC wafers with a 10 m thick epi-layer doped with ͑1-4͒ ϫ 10 16 cm −3 of nitrogen were used to fabricate the MOS capacitor test structures. After undergoing a standard RCA wafer cleaning process with a final 2 min hydrofluoric acid ͑HF͒ dip, an ultrathin SiN ͑7 nm thick͒ layer was deposited on the 4H-SiC substrate using a remote PECVD system with a deposition rate of 1...
