A SiGe/Si Nanostructure with Graphene Absorbent for Long Wavelength Infrared Detection

As a representative of new semiconductor nanostructured materials, the Si 0.7 Ge 0.3 /Si multilayers have received extensive attention for electronic and photonic applications. We fabricated an uncooled detector consisting of a four-period intrinsic Si 0.7 Ge 0.3 /Si multilayer as an active part and two p-type doped electrodes (a PIP profile) for long wavelength infrared detection. The strain in the SiGe/Si multilayer was characterized globally by high-resolution X-ray diffraction (HRXRD) and locally by nanobeam diffraction (NBD) in a high-resolution transmission electron microscope. The performance of detectors was characterized by the temperature coefficient of resistance (TCR), voltage noise power spectral density, and dark current measurement. The detectors with graphene on the top electrode show an improvement for TCR from −2.65%/K to −3.94%/K. Based on our results, the SiGe/Si multilayer structure is an excellent thermal imaging material due to its excellent thermal response as well as its CMOS compatibility.