في هذا العمل ، يتم الإبلاغ عن ترانسيستور الإلكتروليتي العمودي (VET) الذي يستند بنيته إلى طبقات متعامدة كما هو موضح أدناه: الاتصال السفلي (مصدر أو مخرج) - قناة - الإلكترد الوسيط المتصلب (مخرج أو مصدر) - جيل الآيون (الإلكتروليت المغناطيسي للحافظ) - اتصال رأس الحافظ. يصور هذا الVET المتعدد الاستخدامات للعمل كمفتاح الميدان العمودي العضوي المضاد للإلكتروليت (Electrolyte-Gated VOFET) أو ترانسيستور الإلكتروكيمي العمودي (VOECT) كما لم يتم الإبلاغ عنه من قبل. التمييز بين هذه الطرق العمل يتعلق بالسحب الترانسيستور الذي يحدث بسبب الحاملين المحددين أو التيار الآيوني على التوالي. كلا الطرق العمل تظهر أن هذا الVET يمكن أن يعمل في مجال فولتية بطيئة جدًا ويقوم بتحميل ترانسيستانس عالي الكثافة. يجعل هذه الخصائص الملاحظة VETs مرشحا جيدا للتطبيقات في أجهزة آيونترونية وأجهزة الاستشعار الحيوي و / أو حلول الطاقة الضئيلة الضوئية الكهربائية.
In this work it is reported a vertical electrolyte transistor (VET) whose structure is based on stacked layers as described below: bottom contact (source or drain) - channel - permeable intermediate electrode (drain or source) - ion gel (electrolyte gate dielectric) - gate top contact. This VET depicts versatility to work as Electrolyte-Gated Vertical Organic Field Effect Transistor (Electrolyte-Gated VOFET) or Vertical Organic Electrochemical Transistor (VOECT) as never reported before. The distinction of these operation modes is regarding to the transistor transconductance that occurs due to induced charge carriers or ionic current, respectively. Both modes of operation show that this VET is able to work at very low voltage range and drive a high current density. These observed features make VETs a good candidate for applications in iontronic devices, bio-sensors and/or very low power optoelectronic circuits.
We present a novel, graphene-based device concept for high-frequency operation: a hot electron graphene base transistor (GBT). Simulations show that GBTs have high current on/off ratios and high current gain. Simulations and small-signal models indicate that it potentially allows THz operation. Based on energy band considerations we propose a specific materials solution that is compatible with SiGe process lines.
The high-throughput scalable production of cheap, efficient and durable electrocatalysts that work well at high current densities demanded by industry is a great challenge for the large-scale implementation of electrochemical technologies. Here we report the production of a 2D MoS2-based ink-type electrocatalyst by a scalable top-down exfoliation technique followed by a simple heat treatment. The catalyst shows a high current density of 1000 mA cm^-2 at an overpotential of 454 mV for the hydrogen evolution reaction (HER) without the need of iR correction, as well as good stability over 24 hours. Using the same method, we have, for the first time, produced a cheap MoS2 mineral-based catalyst and found that it had an excellent performance for high-current-density HER. Noteworthy, production rate of this MoS2-based catalyst is one to two orders of magnitude higher than those previously reported. In addition, the price of the MoS2 mineral is five orders of magnitude lower than commercial Pt catalysts, making the MoS2 mineral-based catalyst cheap, and the ink-type catalyst dispersions can be easily integrated with other technologies for large-scale catalyst electrode preparation. These advantages indicate the huge potentials of this method and mineral-based cheap and abundant natural resources as catalysts in the electrochemical technologies.
A procedure to achieve the density-controlled growth of gold-catalyzed InP nanowires (NWs) on (111) silicon substrates using the vapor-liquid-solid method by molecular beam epitaxy is reported. We develop an effective and mask-free method based on controlling the number and the size of the Au-In catalyst droplets in addition to the conditions for the NW nucleation. We show that the NW density can be tuned with values in the range of 18 {mu}m-2 to < 0.1 {mu}m-2 by the suitable choice of the In/Au catalyst beam equivalent pressure (BEP) ratio, by the phosphorous BEP and the growth temperature. The same degree of control is transferred to InAs/InP quantum dot-nanowires, taking advantage of the ultra-low density to study by micro-photoluminescence the optical properties of a single quantum dot-nanowires emitting in the telecom band monolithically grown on silicon. Optical spectroscopy at cryogenic temperature successfully confirmed the relevance of our method to excite single InAs quantum dots on the as-grown sample, which opens the path for large-scale applications based on single quantum dot-nanowire devices integrated on silicon.
Voltage-induced ferromagnetic resonance (V-FMR) in magnetic tunnel junctions (MTJs) with a W buffer is investigated. Perpendicular magnetic anisotropy (PMA) energy is controlled by both thickness of a CoFeB free layer deposited directly on the W buffer and a post-annealing process at different temperatures. The PMA energy as well as the magnetization damping are determined by analysing field-dependent FMR signals in different field geometries. An optimized MTJ structure enabled excitation of V-FMR at frequencies exceeding 30 GHz. The macrospin modelling is used to analyse the field- and angular-dependence of the V-FMR signal and to support experimental magnetization damping extraction.
We present the combined analysis of the electroluminescence (EL) as well as the current-voltage (I-V) behavior of single, freestanding (In,Ga)N/GaN nanowire (NW) light-emitting diodes (LEDs) in an unprocessed, self-assembled ensemble grown by molecular beam epitaxy. The data were acquired in a scanning electron microscope equipped with a micromanipulator and a luminescence detection system. Single NW spectra consist of emission lines originating from different quantum wells, and the width of the spectra increases with decreasing peak emission energy. The corresponding I-V characteristics are described well by the modified Shockley equation. The key advantage of this measurement approach is the possibility to correlate the EL intensity of a single NW LED with the actual current density in this NW. This way, the external quantum efficiency (EQE) can be investigated as a function of the current in a single NW LED. The comparison of the EQE characteristic of single NWs and the ensemble device allows a quite accurate determination of the actual number of emitting NWs in the working ensemble LED and the respective current densities in its individual NWs. This information is decisive for a meaningful and comprehensive characterization of a NW ensemble device, rendering the measurement approach employed here a very powerful analysis tool.