Preparation And Basic Research Of Artificial Microstructure Based On HEMT In Terahertz Band

Terahertz(Terahertz, 1THz = 1012Hz) generally refers to the electromagnetic radiation with the frequency range of 0.1THz to 10THz(wavelength range of 3mm to 30μm). Terahertz waves in the electromagnetic spectrum occupy a very special place, which has a superior academic value and unique characteristics. THz wireless communication, as the most important application direction in the terahertz areas, is currently subject to the attention of the world. While as one of the most critical core technology in the terahertz communication systems, terahertz dynamic function devices such as terahertz switches, modulators, filters, etc., have now become the focus of terahertz science and technology research. In recent years, with the development of semiconductor materials and technology, high electron mobility transistor(HEMT) demonstrated excellent performance, which provides a new idea for achieving dynamic terahertz device.HEMT is a new type of field-effect transistor,which uses two-dimensional electron gas(2-DEG) exists in the modulation doped heterostructures to carry out the work. The appearance of HEMT provides new thinking for the development of terahertz rapid response dynamic devices. The third-generation wide bandgap semiconductor material—GaN,not only has a wide bandgap(which leading power output), but also has other characteristics,such as high concentrations of carrier, high electron saturation velocity(which leading short transit time), high breakdown field strength and good thermal stability. Therefore, in the preparation of high-speed dynamic functional devices, GaN-based HEMT has a great advantage.The following results have been achieved in this thesis:1. we focus on the key process which affects the performance of the AlGaN/GaN HEMT devices, and fabricate the devices on the basis of the optimization of process parameters.First we introduces lithography, ICP etching process for isolation of the active region briefly, followed,effects of the surface treatment, annealing conditions and metal components on ohmic contact of AlGaN/GaN HEMT are studied.Study results obtained optimum conditions of Ti/Al/Ni/Au ohmic contact. Finally,Combined with the optimized parameters have achieved, an then fabricate the AlGaN/GaN HEMT devices.2. Analyzed the designing methods of terahertz dynamic device based on metamaterials, then analyzed and studied electromagnetic properties of two ELC metamaterials cell structures.3. By structure design,simulation and optimization,designed a terahertz modulator which combining HEMT with metamaterials.And prepared the modulator by the way of MEMS.By analyzing the test results,the modulator has fast modulation action for terahertz waves that close to the designed frequency.This confirmed the reliability and accuracy of the preparation methods and process parameters used in the devices.Preparation of devices involved in this paper were done in Suzhou Institute of nano technology and nano bionic.