▎ 摘　　要

Silicon-based devices keep moving into smaller dimension for improving the speed, efficiency, and low-power consumption. Novel designed semiconductor device architectures are needed to overcome the physical limitations. An integration of well-designed nanostructure and nanomaterials can potentially establish new principles and approaches to nanoelectronic and photonic devices. We herein demonstrate a graphene/SiO2/p-Si (GOS) heterostructure with an embedded nanoscale mesa, forming a GOS-Mesa field-effect photodetector. The proposed structure exhibits that multiple exciton generation (MEG) can occur in a quantum-confined two-dimensional electron gas (2DEG) region via impact ionization, leading to high internal quantum efficiency (eta(IQE)). The numerical simulation of the carrier multiplication (CM) factor in our designed structure finds a reasonable agreement with empirical data. Simulated and measured internal quantum efficiency demonstrate similar to 195% and similar to 135% of UV-Vis radiation, respectively. A vertically confined 2DEG plays an important role not only in enabling the electron emission process which is responsible for the flowing of electron current, but also in developing a highly localized electric field (up to similar to 10(6) V/cm) at the SiO2/Si interface, enabling an impact ionization process under photon energy of merely similar to 1.95 eV. Our findings demonstrate that carrier multiplication can be achieved in a suitably designed nanoscale structure in conjunction with nanomaterial on silicon-based devices, providing incentive to better understand MEG within quantum wells in 2DEG systems, and being a research path to enhancing the efficiency of future solar harvesting technologies. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim