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   Direct electro-optical pumping for hybrid CdSe nanocrystal/III-nitride based nano-light-emitting diodes; ; et al in Applied Physics Letters (2016), 108 We propose a device concept for a hybrid nanocrystal/III-nitride based nano-LED. Our approach is based on the direct electro-optical pumping of nanocrystals (secondary excitation) by electrically driven ... [more ▼] We propose a device concept for a hybrid nanocrystal/III-nitride based nano-LED. Our approach is based on the direct electro-optical pumping of nanocrystals (secondary excitation) by electrically driven InGaN/GaN nano-LEDs as the primary excitation source. To this end, a universal hybrid optoelectronic platform was developed for a large range of optically active nano- and mesoscopic structures. The advantage of the approach is that the emission of the nanocrystals can be electrically induced without the need of contacting them. The proof of principal was demonstrated for the electro-optical pumping of CdSe nanocrystals. The nano-LEDs with a diameter of 100 nm exhibit a very low current of 8 nA at 5V bias which is several orders of magnitude smaller than for those conventionally used. The leakage currents in the device layout were typically in the range of 8 pA to 20 pA/cm2 at 5V bias. The photon-photon down conversion efficiency was determined to be 27%. Microphotoluminescence and microelectroluminescence characterization demonstrate the potential for future optoelectronics and highly secure “green” information technology applications. [less ▲] Detailed reference viewed: 139 (9 UL)Reduction of skin effect losses in double-level-T-gate structure; ; et al in Applied Physics Letters (2014), 105 We developed a T-gate technology based on selective wet etching yielding 200 nm wide T-gate structures used for fabrication of High Electron Mobility Transistors (HEMT). Major advantages of our process ... [more ▼] We developed a T-gate technology based on selective wet etching yielding 200 nm wide T-gate structures used for fabrication of High Electron Mobility Transistors (HEMT). Major advantages of our process are the use of only standard photolithographic process and the ability to generate T-gate stacks. A HEMT fabricated on AlGaN/GaN/sapphire with gate length Lg=200 nm and double-stacked T-gates exhibits 60 GHz cutoff frequency showing ten-fold improvement compared to 6 GHz for the same device with 2 um gate length. HEMTs with a double-level-T-gate (DLTG) structure exhibit up to 35% improvement of fmax value compared to a single T-gate device. This indicates a significant reduction of skin effect losses in DLTG structure compared to its standard T-gate counterpart. These results agree with the theoretical predictions. [less ▲] Detailed reference viewed: 168 (0 UL)Impact of thermal annealing on nonequilibrium carrier dynamics in single-crystal, freestanding GaAs mesostructures; ; et al in Semiconductor Science & Technology (2014), 29 We report on the impact of thermal annealing to carrier transport and transient, subpicosecond photoresponse of freestanding GaAs mesostructures. Our measurements included micro-photoluminescence and dark ... [more ▼] We report on the impact of thermal annealing to carrier transport and transient, subpicosecond photoresponse of freestanding GaAs mesostructures. Our measurements included micro-photoluminescence and dark current and responsivity studies as well as optical femtosecond characterization. The fabricated GaAs mesostructures consisted of both mesowires and platelets that were integrated into coplanar striplines to form a photoconductive switch. We demonstrate that an optimized annealing process of our mesostructures, performed at 600 ◦C for 20 min, led to restoring bulklike properties of our freestanding devices. They exhibited dark currents below 600 pA at 10 V bias, responsivity of 0.2 A W−1 at 30 V, and mobility as high as 7300 cm2 V s−1. The annealed freestanding GaAs photodetectors were characterized by subpicosecond carrier relaxation dynamics with negligible trapping and a cutoff frequency of 1.3 THz. The latter characteristics make them excellent candidates for THz-bandwidth optoelectronics. [less ▲] Detailed reference viewed: 153 (2 UL)Highly Transparent Conducting Polymer Top Contacts for Future III–Nitride Based Single Photon Emitters; ; et al in Japanese Journal of Applied Physics (2013), 52 Detailed reference viewed: 211 (6 UL)Tuning the spectral sensitivity of vertical InN nanopyramid based photodetectors by means of band gap engineering and/or nanostructure size control; ; et al in ASDAM 2012, The Ninth International Conference on Advanced Semiconductor Devices and Microsystems (2012) Detailed reference viewed: 127 (0 UL)GaAs nanowhiskers for femtosecond photodetectors and THz emitters; ; et al in ASDAM 2012, The Ninth International Conference on Advanced Semiconductor Devices and Microsystems (2012) Detailed reference viewed: 161 (0 UL)Towards future III-nitride based THz OEICs in the UV range; ; et al in ASDAM 2012, The Ninth International Conference on Advanced Semiconductor Devices and Microsystems (2012) Detailed reference viewed: 112 (0 UL)Femtosecond and highly sensitive GaAs metal–semiconductor–metal photodetectors grown on aluminum mirrors/pseudo-substrates,; ; et al in Semiconductor Science & Technology (2010), 25(7), 75001 Detailed reference viewed: 126 (0 UL) |
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