In this study, a high-performance AlGaN/GaN high electron mobility transistor (HEMT) is presented to improve its electrical operation by employing an inner field-plate (IFP) structure. Prior to the IFP structure analysis, we compared the measured and simulated direct current characteristics of the fabricated two-finger conventional T-shaped gate HEMTs. Then, the AlGaN/GaN HEMT with a drain-side field plate (FP) structure was suggested to enhance the breakdown voltage characteristics. The maximum breakdown voltage recorded with a 0.8 µm stretched FP structure was 669 V. Finally, the IFP structure was interfaced with the gate head of the device to compensate the radio frequency characteristics, choosing the optimum length of the drain-side FP structure. Compared to the 0.8 µm stretched FP structure, the IFP structure showed improved frequency characteristics with minimal difference to the breakdown voltage. The frequency variation caused by changing the passivation thickness was also analyzed, and the optimum thickness was identified. Thus, IFP AlGaN/GaN HEMT is a promising candidate for high-power and high-frequency applications.

In this study, we investigated the operational characteristics of AlGaN/GaN high electron mobility transistors (HEMTs) by applying the copper-filled trench and via structures for improved heat dissipation. Therefore, we used a basic T-gate HEMT device to construct the thermal structures. To identify the heat flow across the device structure, a thermal conductivity model and the heat transfer properties corresponding to the GaN, SiC, and Cu materials were applied. Initially, we simulated the direct current (DC) characteristics of a basic GaN on SiC HEMT to confirm the self-heating effect on AlGaN/GaN HEMT. Then, to verify the heat sink effect of the copper-filled thermal structures, we compared the DC characteristics such as the threshold voltage, transconductance, saturation current, and breakdown voltage. Finally, we estimated and compared the lattice temperature of a two-dimensional electron gas channel, the vertical lattice temperature near the drain-side gate head edge, and the transient thermal analysis for the copper-filled thermal trench and via structures. Through this study, we could optimize the operational characteristics of the device by applying an effective heat dissipation structure to the AlGaN/GaN HEMT.

This study proves synthesis of carbohydrate polymer phytagel based composite proton exchange membranes and employed for their applications in proton exchange membrane fuel cells. Phytagel was sulfonated using chlorosulfonic acid and corresponding composite membranes were prepared by loading different amounts of sulfamic acid (SA) to improve their proton conductivity.

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