Graphene nanoribbons show unique properties and have attracted a lot of attention in the recent past. Intensive theoretical and experimental studies on such nanostructures at both the fundamental and application-oriented levels have been performed. The present paper discusses the suitability of graphene nanoribbons devices for nanoelectronics and focuses on three specific device types -graphene nanoribbon MOSFETs, side-gate transistors, and three terminal junctions. It is shown that, on the one hand, experimental devices of each type of the three nanoribbon-based structures have been reported, that promising performance of these devices has been demonstrated and/or predicted, and that in part they possess functionalities not attainable with conventional semiconductor devices. On the other hand, it is emphasized that -in spite of the remarkable progress achieved during the past 10 yearsgraphene nanoribbon devices still face a lot of problems and that their prospects for future applications remain unclear.

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We report on the intrinsically limited low-field mobility of the two-dimensional electron gas (2DEG) in gated AlGaN/GaN and AlGaN/AlN/GaN heterostructures. Monte Carlo transport simulations are carried out to calculate the room-temperature 2DEG mobilities in dependence on the electron sheet density. The simulated 2DEG mobilities are compared to the phonon-limited mobility of bulk GaN. We estimate a maximum 2DEG mobility of about 2700 cm2 V−1 s−1 for an electron sheet density of ∼5×1012 cm−2, which remarkably exceeds the phonon-limited bulk mobility of 1520 cm2 V−1 s−1. By reducing the electron sheet density below 5×1012 cm−2, i.e., in a weak electron quantum confinement regime, the room-temperature 2DEG mobility gradually decreases and approaches the phonon-limited bulk value for vanishing quantum confinement. The insertion of a thin AlN barrier interlayer improves transport properties of the 2DEG and the mobility substantially increases due to a suppression of the alloy scattering.

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To obtain detailed information on structural and electrical properties of AlGaN/GaN Schottky diodes and to determine an appropriate equivalent circuit, impedance spectroscopy and impedance voltage profiling are employed over a frequency range of 1 MHz–1 Hz. In contrast to the commonly assumed parallel connection of capacitive and resistive elements, an equivalent circuit is derived from impedance spectra which utilizes the constant phase element and accounts for frequency dispersion and trap states. The trap density is estimated and is in good agreement with the literature values. The resulting reduced equivalent circuit consists of a capacitor and resistor connected in series.