Research Of Terahertz Modulator Based On HEMT Structure

As the terahertz technology has become a focus of research in the world, at the same time, domestic research has being prevailed. As a important part in T Hz wireless communication system and THz imaging system- THz modulator becomes an indispensable research part. It has lots of reports about terahertz modulation technology, about the aspect of materials include semiconductor, graphene, VO 2, photonic crystals, metamaterials, etc; about the aspect of modulation ways include electric, temperature, optical, etc. But different modulation technologies have their disadvantages. For example, preparation of electrical graphene modulator is simple and its modulation speed is faster, but modulation depth is shallow; thermal VO 2 modulator gets deep modulation depth, but its modulation speed is slow. The combination of semiconductor such as Si and Ga As and metamaterials is an important way of terahertz modulation technology, its modulation speed only achieves kHz order of magnitude because the effect of the carrier mobility.This paper puts forward a structure terahertz modulator based on high electron mobility transistor, through voltage way controls the AlGaN/GaN heteros tructure interface two dimensional electron gas concentration, the modulator can realize fast modulation for terahertz wave. After research of high electron mobility transistor layout drawing and process preparation, obtain the fine electrical performance transistor through explore the steps in the process. On this basis, using the software designs, simulates and optimizes metamaterials structure in order to make its resonant frequency point move the ideal frequency band. Draw the combination of high electron mobility transistor and metamaterials modulator cell layout and arrange them into a whole modulator, then produce the experimental mask. Under the condition of the technological process and parameters, modulator preparation succeeded. By applied voltage on modulator gate control AlGaN/GaN heterostructure interface two dimensional electron gas concentration to on-off transistor, the modulator combined with metamaterials will modulate terahertz wave. After testing the modulator performance of transmissivity and dynamic modulation, we can get the modulator maximum modulation depth is 18% and modulation speed can reach 3MHz.This paper puts forward a structure terahertz modulator based on high electron mobility transistor, it can be compatible with Ⅲ- Ⅴ compound semiconductor technological process. The modulator can be used in condition of coupling of dynamic electrical signal and terahertz wave, it also can be used in the terahertz system as a functional device, it have great potential and value in the terahertz wireless communication, detection and imaging application.