Research On InP-based Resonant Tunneling Diode And Its Oscillator In The Terahertz Band

Recently,the unique properties of the terahertz(THz)wave have made it show great potential in high-speed wireless communications,security imaging and other applications.For these applications,compact and room temperature operating solid-state sources are key components.Owning the high fundamental oscillation frequency and room temperature operation,InP-based resonant tunneling diodes(RTDs)have been considered as a fantastic candidate for THz oscillators.However,the applications of RTD oscillator are limited by the low output power(less than 1 mW).This article aims to lay the foundation for improving the output power of RTD oscillators by conducting related research.There are four main contributions in optimization design material structure of RTD,RTD device fabrication process capable of accurately controlling junction area,testing and modeling of RTD device and impedance matching of RTD oscillation circuit.1.We have theoretically and experimentally demonstrated a high power density strained In0.8Ga0.2As/AlAs RTD by optimizing emitter spacer thickness for THz radiation.Appropriate increasing ESL thickness will increase current and voltage widths of negative differential resistance(NDR)region simultaneously.2.The junction area of RTD device directly determines its frequency characteristics and power characteristics.We developed the fabrication process which can precisely control mesa area of RTDs,thus ensuring the stability of the electrical performance of the RTD device at the fabrication process level.3.Due to the presence of low-frequency oscillations,the capacitance of RTD is difficult to extract.We have measured scattering parameters of RTD device and extracted the junction capacitance at high frequency band(3 GHz to 40 GHz).This method can avoid the influence of low-frequency oscillation.4.We propose an impedance matching design method to increase output power of RTD oscillator.We have studied the rule that the output power of different junction area RTD oscillator corresponds to the best matching load,and proposed a method for specific impedance matching for different junction area.