In this paper, high performance InGaN double channel (DC) high electron mobility transistors (HEMTs) are proposed and systematically investigated. Due to the coordination of double InGaN channels, a large maximum drain current density and a distinct double-hump feature of the transconductance and frequency performance are achieved. More importantly, it is revealed that the coupling effect between the two InGaN channels is much stronger than that of the conventional GaN DC HEMTs. This characteristic leads to a remarkable enhancement in the gate voltage swing, indicating the excellent linearity of the InGaN DC HEMTs at both dc and rf conditions. Benefiting from the enhanced electron confinement in InGaN channels, the fabricated HEMTs show a low off state drain leakage current of 0.26 μA/mm and a high on/off current ratio (I_on/I_off) of 5.1 × 10⁶. In addition, the desirable current collapse and breakdown characteristics are also obtained. This work convincingly demonstrates the great potential and practicality of the InGaN DC HEMTs for high power and high bandwidth applications.

The conventional and inverted organic solar cells (OSC and IOSC) based on the bulk heterojunction structure are investigated from both optical and electrical aspects. When the optical aspect is considered only, with the increase of the active layer thickness, the number of photons absorbed in the active layer and the external quantum efficiency tend to increase with the obvious interference behavior for both OSC and IOSC. However, compared to OSC, IOSC shows a better performance except for the thicknesses around which the interference maxima of OSC are obtained. When the electrical aspect is also considered, an effective area in the active layer will be induced by the charge drift length (L), and only the photons absorbed in this effective area have contribution to the photocurrent. By considering optical and electrical aspects together, OSC and IOSC show different behaviors. Compared to IOSC, OSC performs better for relatively thick active layers. Simultaneously, the optical modulation effect is also investigated by introducing an optical spacer layer. It is found that the optical spacer layer can notably enhance the performance of OSC with thin and thick active layers, while it could only degrade the performance of IOSC with relatively thick active layers.

The single event burn-out (SEB) performances of p-GaN gate high electron mobility transistors (HEMTs) were investigated in this article, considering different buffer electron mobilities and incident depths. The output, transfer, and breakdown curves of p-GaN gate HEMTs are not affected by the buffer electron mobility. However, a decrease in buffer electron mobility from 1350 to 265 cm $^{\text{2}}$ /(V $\cdot$ s) leads to an increase in SEB voltage from 340 to 460 V. After heavy ion impact, a significant number of electron–hole pairs are generated within the device. Gate breakdown occurs when the electric field at the gate exceeds the critical breakdown strength. Subsequently, an increase in device current is observed, leading to local temperature in HEMT up to 2000 K. The localized high temperature induces the occurrence of SEB. Heavy ion strikes into the buffer layer significantly deteriorate the SEB characteristics. As the incident depth of heavy ion increases, the transient current and device temperature increase correspondingly. Simulation results indicate that the buffer layer has a great effect on SEB characteristics of p-GaN gate HEMTs.