1National Engineering Research Center of Electromagnetic Radiation Control Materials, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
2State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
3Key Laboratory of Multi-Spectral Absorbing Materials and Structures of Ministry of Education, University of Electronic Science and Technology of China, Chengdu 610054, China
Siyu Zhou, Bo Peng. Non-volatile optical memory in vertical van der Waals heterostructures[J]. Journal of Semiconductors, 2020, 41(7): 072906
Copy Citation Text
Fig. 1. (Color online) Device schematic. (a) Device with three-layer structure of graphene/CdSe QDs/graphene, silver as the electrodes on each graphene. (b) Circuit connection diagram of the devices.
Fig. 2. (Color online) (a) Illumination time dependence of output current of a conventional commercial Si photodetector (blue) and our ORRAM synaptic device (red). (b) The non-volatile optical storage characteristic of the ORRAM device. A laser pulse of 637 nm with 0.2 mW/cm2 is used to write; a 0.5 V bias is applied to read. The pulse width is 3 s. (c) The absorption and photoluminescence spectra of CdSe QDs. (d) Under the light illumination at 980 and 637 nm, the relative increase of Ids of the device under three laser pulses respectively. Under 637 nm excitation, the photocurrent significantly increase, even the bias is halved.
Fig. 3. (Color online) (a) Band offset of Ag, graphene and CdSe QDs. (b) Energy band alignment of graphene and CdSe QDs in the heterojunctions. (c) The gate voltage dependence of Ids under bias of 1 V. (d) Schematic of electrons migration, accumulation and tunneling.
Fig. 4. (Color online) (a–c) The multi-level resistance states of the ORRAM device under different laser power and bias voltages. (d) Corresponding 2D mapping of ΔIds as a function of bias voltages and laser power.