Terahertz Quantum Well Photodetectors With Metal-Grating Couplers

In this paper, terahertz (THz) quantum well photodetectors (QWPs) with metal-grating couplers are presented for normal-incident operation. Both one-dimensional and two-dimensional grating samples were fabricated. The photocurrent spectra and the peak responsivity were characterized. The effects of the grating period, fill factor, and shape of the grating patch were investigated. It is found that metal gratings are simple but efficient couplers for THz QWPs, and compared with the 45°-incident facet sample, the peak responsivity of the THz QWP with the optimum grating coupler is improved by 146%.