Visible and infrared photodiode based on γ-InSe/Ge van der Waals heterojunction for polarized detection and imaging

Abstract

Broadband photodetectors are a category of optoelectronic devices that have important applications in modern communication information. γ-InSe is a newly developed two-dimensional (2D) layered semiconductor with an air-stable, low-symmetry crystal...

Type-II Bi2O2Se/MoTe2 van der Waals Heterostructure Photodetectors with High Gate-Modulation Photovoltaic Performance

“…To estimate the level of the photodetection performance for Bi 2 O 2 Se/MoTe 2 , key factors such as R = I ph / PA and D * = R √ A / S n were calculated, − where A is the effective area of the photodetector and S n is the noise spectral density. Considering the fast speed of the device, S n can be extracted at a frequency of 20 Hz.…”

Vertical 1T’‐WTe2/WS2 Schottky‐Barrier Phototransistor with Polarity‐Switching Behavior

“…The above parameters serve as a crucial metric to assess the level of our fabricated reconfig-urable phototransistor, which can be calculated by the following formulas. [58] R = I ph ∕P in S…”

“…At last, to absolutely evaluate the sensitivity of the self-driven photodetector without V g , D* should be calculated by the following formula. [58]…”

“…The above parameters serve as a crucial metric to assess the level of our fabricated reconfigurable phototransistor, which can be calculated by the following formulas. [ 58 ] $$$$\begin{equation}R\ = {I}_{ph}/{P}_{in}S\end{equation}$$$$ $$$$\begin{equation}EQE\ = \ \frac{{Rhc}}{{q\lambda }}\end{equation}$$$$ $$$$\begin{equation}{D}^{\mathrm{*}} = \frac{{R\sqrt A }}{{\sqrt {2q{I}_{dark}} }}\ \end{equation}$$$$ $$$$\begin{equation}NEP\ = \ \frac{{{i}_n}}{R}\end{equation}$$$$Where S is the effective illumination area determined by the photocurrent mapping results at V g = ± 60 V, P in is the incident light power density, and I ph is the net photocurrent. Moreover, q is the electronic charge, h is Planck's constant, c is the velocity of light, and λ is the incident wavelength.…”

“…To compare the photovoltaic performance of WTe 2 /WS 2 phototransistor at different photocurrent signs, Figure 4h depicts I ph and R as a function of P at V g = ‐60 V and 60 V. Herein, the parameter sign is omitted to enhance evaluation accuracy. Remarkably, I ph monotonously increases with the increasing P because of the larger number of photo‐generated electron‐hole pairs being separated by the built‐in electric field under stronger P. According to the power law formula of $${I}_{ph}\ \propto \ P_{in}^{\ \alpha }$$, [ 58 ] the fitting index of α are extracted to be 0.95 (< 1) at V g = 60 V and 0.82 (< 1) at V g = ‐60 V after fitting the experimental data. The clear sub‐linear power‐dependent behavior of the photocurrent is obtained under the gate‐modulation photovoltaic effect.…”