High-performing silicon-based germanium Schottky photodetector with ITO transparent electrode* *Project supported by the National Key Research and Development Program of China (Grant No. 2018YFB2200103), the National Natural Science Foundation of China (Grant No. 61474094), and Principal Fund of Minnan Normal University (Grant No. KJ2020006).

Abstract

A near-infrared germanium (Ge) Schottky photodetector (PD) with an ultrathin silicon (Si) barrier enhancement layer between the indium-doped tin oxide (ITO) electrode and Ge epilayer on Si or silicon-on-insulator (SOI) is proposed and fabricated. The well-behaved ITO/Si cap/Ge Schottky junctions without intentional doping process for the Ge epilayer are formed on the Si and SOI substrates. The Si- and SOI-based ITO/Si cap/Ge Schottky PDs exhibit low dark current densities of 33 mA/cm2 and 44 mA/cm2, respectively. Benefited from the high transmissivity of ITO electrode and the reflectivity of SOI substrate, an optical responsivity of 0.19 A/W at 1550 nm wavelength is obtained for the SOI-based ITO/Si cap/Ge Schottky PD. These complementary metal–oxide–semiconductor (CMOS) compatible Si (or SOI)-based ITO/Si cap/Ge Schottky PDs are quite useful for detecting near-infrared wavelengths with high efficiency.