Contents I. Introduction
Wireless power transmission (WPT) is a promising technology with broader application prospects in many fields, such as medical care, electric vehicles, and the industrial Internet of Things (IIoT) [1], [2], [3], [4]. Rectifiers being one of the core components of WPT system, its performance directly affects the power capacity, efficiency, and working distance of the system. The active devices, such as Schottky barrier diodes (SBDs), have been identified as one of the limiting factors for improving the core performance of the rectifier, i.e., the conversion efficiency and bandwidth. In recent years, rectifiers based on silicon (Si) and gallium arsenides (GaAs) SBDs have been widely reported [5], [6], [7], [8], [9], [10], [11]. Nevertheless, the efficiency of these rectifiers still hovers at approximately 80%. To improve the performance of the rectifier, different harmonic termination techniques, such as Class C, Class D, and Class F () rectifier circuits, are proposed to reshape the diode current and voltage waveforms [12], [13], [14], thereby reducing power loss in the diode. However, the efficiency improvement of the rectifiers is limited due to the extra losses introduced by the additional circuit, and the load bandwidth is also sacrificed. Obviously, a customized SBD with improved performance, such as low (series resistance), (junction capacitance), (built-in potential), and high (breakdown voltage), is the key to enhance the rectifier efficiency and operational bandwidth. However, it is very difficult to achieve all of them simultaneously even with a GaN-based SBD [15], [16] because the aforementioned parameters often impose constraints on each other.
