We demonstrate an atomic-sized Pd tunneling junction memory that can operate in a vacuum, N2, or ambient environment. The device was fabricated by a simple 2-step electron-beam lithography/lift-off process and an electromigration process. Calculation based on quantum point contact model indicated the size of the tunneling gap is between 0.1 and 2nm, and the switching between high-resistance state and low-resistance state is achieved by a migration of a few atoms near the junction. The device’s RESET speed is 25ns, and the ON/OFF ratio is from 2 to 103, with an endurance of 1000 cycles. We proposed a phenomenological model to explain the reason for the imperfection of device performance, which could be useful for circuit design. It may be derived from two different migration processes, dominated by rapid changing electric field and current-induced Joule heat accumulation to affect the device performance, respectively. Compared to other reported works, our devices have the same fast RESET speed, better endurance, and potential for low power applications.

In this paper, we propose and implement a single-electron transistor (SET) based on cobalt oxide for the first time. The SETs were fabricated through nanofabrication process compatible with the CMOS technology. A cobalt oxide (Co1-yO) on the surface of the source (S) and drain (D) Co electrodes is utilized to act as a quantum dot (QD). The diameter of QD is calculated to be 2.3 nm. The interface between Co1-yO and Co thin films (S/D electrodes) is used as tunneling junctions. The SET based on CoO exhibits typical single electron transport characteristics. Owing to the high Coulomb blockade energy (~180 meV), the Coulomb blockade regions still remain at room temperature (300 K), revealing the nanometer scale CoO-based SETs have great potential to operate at room temperature.

In this work, we investigate the performance of radio-frequency (RF) power amplifier based on chemical vapor deposition (CVD) graphene field-effect transistors (GFETs). The GFETs with gate length of 300 nm were fabricated on SiO2/Si substrate, which show an extrinsic current gain cut-off frequency (fT) of 18.6 GHz and an extrinsic maximum oscillation frequency (fmax) of 19.8 GHz. The parameters of compact large-signal model for the GFETs were extracted from the measured direct current (DC) and RF characteristics of GFETs, followed by implementation of the compact model using Verilog-A for circuit simulation. Using electronic design automation (EDA) tools, we designed a GFET-based power amplifier. The power amplifier working at 2.5 GHz shows a gain of ~7 dB, an output power of ~0 dBm (1 mW), a power added efficiency (PAE) of 2.8% and third order intermodulation distortion (IMD) of ~20 dBc, at the 1 dB compression point.