Accumulation of photoinduced carriers at the SiO2/Si interface observed through graphene transport

The accumulation of photoinduced carriers at the SiO2/Si interface was observed via graphene transport. Chemical vapor deposition graphene was transferred to a lightly p-doped silicon substrate with a SiO2 dielectric layer and served as a charge sensor for detecting the accumulation of photoinduced carriers at the SiO2/Si interface. The sample was cooled to 4.2 K to realize an undoped silicon substrate without intrinsic carriers. Photoexcited carriers in the undoped silicon substrate were collected at the SiO2/Si interface via a gate voltage and the carrier polarity was controlled well by the polarity of the gate voltage set during the light illumination. The photoinduced carrier density was determined by the number of photons incident on the silicon substrate with a photon-electron conversion efficiency of about 0.036. These results may provide polarity control of the conduction channel (n- or p-type) in standard Si-MOS structures, paving the way for optically programmable Si-CMOS.