Fig. 2: Stepwise TMD diode and its optoelectronic property.
From: Room-temperature low-threshold avalanche effect in stepwise van-der-Waals homojunction photodiodes
a Dark and photoexcited I–V curves of A# device measured at room temperature. The photoexcited I–V curves were obtained under a 520 nm laser illumination with an increasing intensity from 2.52 nW to 9.97 nW and 25.78 nW. The diode is at forward-conducting, cut-off and reversed breakdown state as it is operated at 0 V < Vex, −1.6 V < Vex < 0 V, and Vex < −1.6 V, respectively. Inset: schematic showing the device structure. b High-angle annular dark-field transmission electron microscope (HAADF-TEM) and energy-dispersive X-ray spectroscopy (EDX) images of A# device. The scale bar is 5 nm. c Raman spectra of 4 layers (L) and 39 L WSe2 measured with a 532 nm laser line. The spectra are normalized to the A1g peak and vertically offset for clarity. d Multiplication factor/gain derived in dark and under illumination, according to the equation G = Id/Ibg and G = (Iph − Id)/Ibg, where Iph represents the photocurrent, Id is the dark current and Ibg denotes the dark-current/photocurrent when G = 16. e Reverse-biased I–V curves of the A# device as the temperature drops from 300 to 240 K.
