Research On Novel Schottky Diodes For 2.45 Ghz Low Input Power Microwave Wireless Energy Transmission

As a new type of power supply method,wireless power transfer（WPT）system breaks through the limitation of traditional transmission lines,can solve the power supply problem in complex scenarios,and can provide cleaner and low-cost energy for hundreds of millions of sensor nodes in the IOT era,so it becomes a hot research topic.With the development of rectifier antenna technology,the efficiency of WPT systems working in medium and high input power scenarios has been greatly improved,however,WPT systems working in low input power scenarios are limited by the core rectifier components,and the efficiency improvement is very little.In view of this,this paper proposes two Schottky diode structures suitable for low input power rectification by optimizing the design from both material and device structure for the core rectifier components in the system in the context of improving the conversion efficiency of low input power WPT system at 2.45 GHz operating frequency.The research work in this paper is as follows:1.Analysis of factors affecting the conversion efficiency of Schottky diodes for low input power rectification:Through the derivation of the conversion efficiency formula at low input power and the analysis of the SPICE parameters scanned by the ADS rectifier circuit,the range of each SPICE parameter suitable for low input power rectification is obtained.The results show that the SPICE parameters that have a large impact on the conversion efficiency are junction resistance,junction capacitance and series resistance,and the breakdown voltage at greater than 3 V basically has no effect on the conversion efficiency of low-input power rectification.This provides guidance for the subsequent design of the device in the direction of optimization.2.Optimized design of Schottky diodes for low input power rectification:Based on the analysis of SPICE parameters that affect the conversion efficiency of Schottky diodes,the paper proposes two new Schottky diodes with optimized design solutions.In the optimized design of Schottky diodes,the energy band structure parameters and the effective mass of electrons in each crystal direction of Ge and Ge_1-xSn_x are extracted using k.p perturbation theory and first-principal simulation,and the junction resistance of the device is reduced from two ideas of crystal direction optimization and energy band modulation,and W/<100>Ge/Ge_0.92Sn_0.08 and Ge_0.88Sn_0.12 are proposed.Two basic Schottky junction designs are proposed.The effect of the Sn content in Ge_1-xSn_x on its forbidden band width and mobility is then determined,and the high mobility properties of the Ge Sn material are used to achieve the purpose of reducing the series resistance.On the basis of the high mobility of Ge Sn materials,an innovative structure was introduced for the gradual doping of Ge_1-xSn_x layers with Sn components,which leads to the bending of the energy band through the gradual change of Sn components and thus creates an accelerated electric field for the purpose of accelerating electron transport,resulting in the formation of W/Ge_1-xSn_x（8%<x<12%）and W/<100>Ge/Ge_1-xSn_x（8%<x<12%）are two complete design solutions.3.Joint simulation of Schottky diodes for low input power rectification:For the proposed two Schottky diode design solutions,the paper uses the joint simulation method of Silvaco and ADS to finalize the device parameter determination and conversion efficiency simulation of the two Schottky diodes.After input impedance matching,the conversion efficiency of the rectifier circuit using the two new Schottky diodes reaches 42%and 42.5%at-20 d Bm input power,respectively,while the conversion efficiency of the rectifier circuit using the conventional Ge based Schottky diodes is only 3%in the same case,indicating that our rectifier device design work achieves the purpose of improving the conversion efficiency of low input power rectification.In summary,this paper proposes an optimization scheme from the perspective of core rectifier devices to improve the conversion efficiency of low-input power WPT systems,and provides an optimization idea from the physical bottom of the devices for WPT system optimization.