@article{raghunathan_baliga_1999, title={Temperature dependence of hole impact ionization coefficients in 4H and 6H-SiC}, volume={43}, ISSN={["0038-1101"]}, DOI={10.1016/S0038-1101(98)00248-2}, abstractNote={Hole impact ionization coefficients have been accurately measured as a function of temperature in both 4H and 6H-SiC using the pulsed electron beam induced current (P-EBIC) technique. For Chynoweth's equation (α=a e−b/E), our measurements gave an ap value of (2.6±0.12)×106/cm and a bp value of (1.5±0.01)×107 V/cm for 6H-SiC at room temperature while the values of ap and bp for 4H-SiC were found to be (3.25±0.3)×106/cm and (1.71±0.04)×107 V/cm, respectively, at room temperature. The coefficient ap was found to decrease with increasing temperature for both polytypes while the coefficient bp remained constant. Based upon this data, the breakdown voltage of the 4H and 6H-SiC devices is predicted to increase with temperature which is an important desirable characteristic for power devices.}, number={2}, journal={SOLID-STATE ELECTRONICS}, author={Raghunathan, R and Baliga, BJ}, year={1999}, month={Feb}, pages={199–211} }
 @article{raghunathan_baliga_1998, title={P-type 4H and 6H-SiC high-voltage Schottky barrier diodes}, volume={19}, ISSN={["0741-3106"]}, DOI={10.1109/55.661168}, abstractNote={High-voltage Schottky barrier diodes have been successfully fabricated for the first time on p-type 4H- and 6H-SiC using Ti as the barrier metal. Good rectification was confirmed at temperatures as high as 250/spl deg/C. The barrier heights were estimated to be 1.8-2.0 eV for 6H-SiC and 1.1-1.5 eV for 4H-SiC at room temperature using both I-V and C-V measurements. The specific on resistance (R/sub on,sp/) for 4H- and 6H-SiC were found to be 25 m/spl Omega/ cm/sup -2/ and 70 m/spl Omega/ cm/sup -2/ at room temperature. A monotonic decrease in resistance occurs with increasing temperature for both polytypes due to increased ionization of dopants. An analytical model is presented to explain the decrease of R/sub on,sp/ with temperature for both 4H and 6H-SiC which fits the experimental data. Critical electric field strength for breakdown was extracted for the first time in both p-type 4H and 6H-SiC using the breakdown voltage and was found to be 2.9/spl times/10/sup 6/ V/cm and 3.3/spl times/10/sup 6/ V/cm, respectively. The breakdown voltage remained fairly constant with temperature for 4H-SiC while it was found to decrease with temperature for 6H-SiC.}, number={3}, journal={IEEE ELECTRON DEVICE LETTERS}, author={Raghunathan, R and Baliga, BJ}, year={1998}, month={Mar}, pages={71–73} }
 @article{raghunathan_baliga_1998, title={Role of defects in producing negative temperature dependence of breakdown voltage in SiC}, volume={72}, ISSN={["0003-6951"]}, DOI={10.1063/1.121591}, abstractNote={Electron beam induced current (EBIC) techniques were employed in order to understand the role of defects on the breakdown characteristics of SiC. EBIC images revealed that certain defects caused enhanced multiplication leading to the catastrophic failures in SiC diodes. The impact ionization coefficients for holes measured at the defective site (αp,eff) were found to be higher than those measured at a nondefective site. Also, αp,eff measured at the defective site was found to increase with increasing temperature in contrast with a defect free diode where αp decreases with increasing temperature, clearly indicating that the defects produce the observed negative temperature coefficient of breakdown voltage in SiC.}, number={24}, journal={APPLIED PHYSICS LETTERS}, author={Raghunathan, R and Baliga, BJ}, year={1998}, month={Jun}, pages={3196–3198} }