Fig. 1. (a) Schematic illustration of the BP photodetector. (b) SEM image of the BP photodetector with Au electrodes. (c) AFM image of BP nanoflakes showing a thickness of ∼20  nm. (d) Representative Raman spectrum of BP.

Fig. 2. (Color online) (a) Power-dependent photocurrent as a function of source-drain voltage (VSD) at 635 nm. (b) Energy diagram illustrating the photocurrent generation with and without bias. (c) Gate-tunable source-drain current (ISD) with and without light illumination. Laser wavelength: 635 nm, VSD=0.1  V. (d) Time-dependent photocurrent at 635 nm with a light power of 400 nW. VSD=0.1  V. (e) Rise time (10% to 90%) and fall time (90% to 10%) of BP photodetector device at 635 nm. (f) Photocurrent and responsivity as functions of the incident light power at 635 nm.

Fig. 3. (Color online) (a) Power-dependent source-drain current (ISD) as a function of the source-drain bias (VSD) at 980 nm. Inset is a zoom in of the ISD–VSD curve. (b) Time-dependent photocurrent under different incident light powers at 980 nm. VSD=0.1  V. (c) Photocurrent and responsivity as functions of the incident light power at 980 nm. (d) Time-dependent photocurrent with varying incident light powers at 1550 nm. VSD=1  V. (e) Rise time (10% to 90%) and fall time (90% to 10%) of our device at 1550 nm. (f) Photocurrent and responsivity as functions of the incident light power at 1550 nm.

Table 1. Comparison of Our BP Photodetector with Previously Reported BP Photodetectors