Photodetectors with armchair graphene nanoribbons and asymmetric source and drain contacts

- Photodetectors having a-GNR channels of 30 unit cells long and 10 C-atoms wide and asymmetric source and drain electrodes (i.e., p-type and n-type metal-contacted graphenes) are assumed.
- Due to the finite potential step induced between such asymmetric electrodes, these types of photodetectors are shown to generate photocurrents under for zero external biases, when illuminated by monochromatic lights in the solar blind UV region (3-5 eV) with quantum efficiencies of ∼27.5-60%.
- Numerical simulations also show responsivities for these photodetectors for zero applied biases are about 10.4-13.4 A/mW.
- The local photocurrents across the a-GNR channel connected between Au/G (p-type source) and Ti/G (n-type drain) electrodes are shown to be concentrated near the source and drain terminals inside the channel, for VGS = 0 and VDS = 0. For |VGS| > 0, local current peaks move away from the electrodes boundaries.
- While for VGS > 0 negative and positive local currents are concentrated near the source and drain regions, respectively. The current polarities alter for VGS < 0.
- At the maximum of the total photocurrent, polarities of local photocurrent change.
- The total currents versus VDS, obtained under illumination and for VGS = 0, shift toward negative current values, with respect to the dark current for the same biasing condition.