| Summary: | 碩士 === 國立中央大學 === 電機工程學系 === 104 === Reducing energy consumption is a major issue today. In the electronic circuits, most of the energy is consumed by power devices. Therefore, to replace silicon power devices by GaN power devices is a priority in the power systems, electric vehicles, UPS systems, power factor correction, etc. For GaN MIS-HEMTs applied in switching circuits, the mechanism of dynamic on-resistance is a problem not yet been fully clarified.
Dynamic on-resistance prompted by the charges trapped by defects so that the conduction current decreases. In this study, GaN-on-Si HEMT wafer was used and Al0.26Ga0.74N/GaN HEMTs and MIS-HEMTs was fabricated. In order to identify the impact of the dynamic characteristics of factors, where the MIS-HEMTs designed different interface treatments of processing: (i) untreated, (ii) in-situ hydrogen/argon plasma treatment, (iii) aqueous hydrochloric acid solution, and (iv) after an aqueous solution of hydrochloric acid with in-situ hydrogen/argon plasma treatment. No correlation was found between results of dynamic on-resistance and hysteresis or interface state density, which means existing other factors. level
For analyzing the recovery of drain current after stress, different bias conditions and stress time was applied. It was found that under the same bias conditions, a longer stress time causes a longer emission time constant. This suggests that the trapped charges located far from 2DEG or electrode undergo repeated emission and trapping in recovery which increases the emission time constant. In the backgating measurement, when the negative bias is applied on substrate, a greater negative bias makes more electrons trapped near to 2DEG, therefore a shorter emission time constant was observed. The number of trapped charges under zero bias condition could change the trend of recovery of drain current seriously. According to the results, the location of trapped charges should be considered to be one of the most important factor to influence recovery curve of drain current. Based on this conclusion, the analysis of dynamic on-resistance and then the design of epitaxy or device process could be improved.
|
|---|
