Fig. 1. (Color online) (a) 3D structure diagram of the graphene/GaAs heterostructure device with interdigitated electrodes. (b) SEM images of graphene/GaAs heterojunction photodetectors with interdigitated electrodes. (c) Raman spectrum of graphene. (d) Graphene/GaAs energy band diagram under illumination.

Fig. 2. (Color online) (a) The I−V curves of GaAs/graphene devices with interdigitated electrodes and standard graphene/GaAs devices under dark conditions and 808 nm illumination (insert: the schematic diagram of standard graphene/GaAs devices). (b) Momentary photoresponse features under 808 nm illumination conditions at zero bias. (c) I−V characteristics of graphene/GaAs heterojunction detectors with interdigitated electrodes of varying widths under dark conditions and 808 nm illumination. (d) I−V characteristics of graphene/GaAs heterojunction detectors with interdigitated electrodes of varying widths under dark conditions and 1064 nm illumination.

Fig. 3. (Color online) (a) I−V and (b) I−T characteristics of the graphene/GaAs heterojunction device with interdigitated electrodes under different light intensities at 808 nm illumination. (c) Biaxial logarithmic depiction of photoelectric current against light intensity. (d) Responsivity and computed specific detectivity for the device versus light intensity. (e) I−V characteristics and (f) I−T characteristics of the graphene/GaAs heterojunction device with interdigitated electrodes under varying light intensities at 1064 nm illumination.

Fig. 4. (Color online) Frequency response of the graphene/GaAs heterojunction photodetector with interdigitated electrodes to 808 nm light at (a) 2 kHz and (b) 9581 Hz. (c) The 3 dB bandwidth of the graphene/GaAs heterojunction detector with interdigitated electrodes. (d) The device’s dynamic rise and fall characteristics under 9581 Hz pulsed light.