Nonvolatile-memory characteristics of SiC nanocrystals with variable oxide thickness and crested tunnel barriers

The electrical characteristics of SiC nanocrystal nonvolatile-memory devices with variable oxide and crested tunnel barriers consisting of a SiO2/Si3N4/SiO2 (ONO) and a Si3N4/SiO2/Si3N4 (NON) layer, respectively, were investigated. The equivalent oxide thickness of the ONO and NON tunnel barriers were about 5.6 nm and 5.2 nm, respectively. When the +/- 13 V bias voltage was applied for 500 ms, the threshold voltage shifts of the SiC-nanocrystal-embedded memory devices with ONO and NON tunnel barriers were about 2.4 V. The operation speeds of the memories with ONO and NON tunnel barriers under the +/- 10 V applied pulse bias were approximately 5 and 20 ms, respectively. The field sensitivity of the ONO tunnel barrier was higher than that of the NON tunnel barrier during electron injection. The tunneling efficiency during the programming/erasing processes could be improved by the engineered tunnel barrier layer. Therefore, the SiC-nanocrystal-embedded memory device with an ONO tunnel barrier can be applied to nonvolatile-memory devices.