Piezotronic and Piezo-Phototronic Effects-Enhanced Core-Shell Structure-Based Nanowire Field-Effect Transistors.

Piezotronic and piezo-phototronic effects have been extensively applied to modulate the performance of advanced electronics and optoelectronics. In this study, to systematically investigate the piezotronic and piezo-phototronic effects in field-effect transistors (FETs), a core-shell structure-based Si/ZnO nanowire heterojunction FET (HJFET) model was established using the finite element method. We performed a sweep analysis of several parameters of the model. The results show that the channel current increases with the channel radial thickness and channel doping concentration, while it decreases with the channel length, gate doping concentration, and gate voltage. Under a tensile strain of 0.39‱, the saturation current change rate can reach 38%. Finally, another core-shell structure-based ZnO/Si nanowire HJFET model with the same parameters was established. The simulation results show that at a compressive strain of -0.39‱, the saturation current change rate is about 18%, which is smaller than that of the Si/ZnO case. Piezoelectric potential and photogenerated electromotive force jointly regulate the carrier distribution in the channel, change the width of the channel depletion layer and the channel conductivity, and thus regulate the channel current. The research results provide a certain degree of reference for the subsequent experimental design of Zn-based HJFETs and are applicable to other kinds of FETs.

A Novel Modulation and Demodulation Method Based on Binary Frequency Shift Keying for Wireless Power and Data-Parallel Transmission.

It is usually necessary but difficult to achieve reliable communication between the primary side and pick-up side in the wireless power transfer (WPT) system due to magnetic interferences. In this paper, a novel parallel transmission method for wireless power and data is proposed, which is based on the frequency shift keying (FSK) modulation and demodulation. The data are transmitted by changing the working frequency of the inverter and then demodulated based on the phase-locked loop (PLL) technology. In this way, the signal before the rectifier circuit for the data demodulation can overcome the influence of power transmission on the data transmission. Finally, a 426 W prototype has been built to verify the effectiveness of the proposed transmission method. The experimental results showed that when the output power changed from tens of watts to hundreds of watts, the data transmission was capable of achieving a stable transmission with a 10 kbps baud rate.