Physics and Optoelectronic Simulation of Photodetectors Based on 2D Materials

Abstract

2D‐material‐based photodetectors (2DMPDs) have attracted broad interest due to their many unique benefits (e.g., their giant photoresponsivity). However, a thorough device‐level simulation, which takes into account optical absorption, electrical transportation, and semiconductor material properties, is still challenging. This study reports the realization of a comprehensive optoelectronic simulation of 2DMPDs in multidimensional and multiphysics domains. This work begins with a simulation of conventional monolayer photoresistor detectors by introducing basic theories and simulation technologies. In particular, the trap effect, which is highly important for regulating the photoresponse of 2D devices, is successfully introduced into the simulation so that very good agreement between the simulation and an experiment is realized. The simulation is extended to popular monolayer phototransistors so that precise quantitative evaluations of the optoelectronic device performance, such as the output characteristics, transfer properties, responsivity, response time, and detectivity, become very convenient. Furthermore, a time‐domain device simulation is implemented, which allows to study the modulation characteristics of 2DMPDs. The device‐level simulation provides a useful platform for studying and optimally designing advanced 2DMPDs. For example, this simulation is convenient for studying the balance between photoresponsivity and response time in 2DMPDs.

Core–Shell Single‐Nanowire Photodetector with Radial Carrier Transport: an Opportunity to Break the Responsivity‐Speed Trade‐off

“…[ 19–21 ] Here we just show the core equations describing the carrier transportation behaviors: where D n ( D p ) is the diffusion coefficient of electron (hole), n ( p ) the electron (hole) concentration, Φ the electrostatic potential, q the electron charge, ε 0 (ε r ) the vacuum (material) dielectric constant, N d ( N a ) the donor (acceptor) concentration, G the generation rate distribution of photogenerated carriers, and U the total bulk recombination rate, which is mainly from the Shockley–Read–Hall (SRH) recombination here. [ 19 ] The Ag and ITO electrode materials ensure the Ohmic contact of the metal/semiconductor junction. The key parameters of the multilayer MoS 2 material used in the simulation are listed in Table 1 , [ 14,15,22 − 26 ] where E g is the bandgap, χ the electron affinity, N c ( N v ) the effective conduction (valence) band density of states, and τ r the SRH lifetime.…”

“…Note that the independence of R on P is due to the absence of the trap effect. [ 19 ] With P = 1 mW cm −2 , the transient response curve of the photodetector is shown in Figure 3b, which indicates that τ = 230 ps (defined by the time taken for the signal current to rise or fall by 90%). These verify that the proposed structure achieves an ultrahigh R without sacrificing the response speed under the special NW design of the photodetector.…”

Theoretical Prediction of Two-Dimensional Materials, Behavior, and Properties

“…A modeling framework for such devices is necessarily multiscale and requires knowledge of not only basic electronics of the underlying 2D materials but also their (semiclassical/quantum) transport characteristics and device geometry. Simulation approaches that can incorporate most of these aspects have been recently proposed, , and Figure b renders an example of a simulated n-type MOSFET . For a design with a sub-10 nm device channel this quantitative framework predicts that 2D As (arsenene , ) or Sb (antimonene , ) used as channel material ensures device characteristics that can meet the practical requirements/targets.…”

Ambipolar Self-Driving Polarized Photodetection

“…Furthermore, the G ( x , y , z , λ) is used to couple from the optical response to the carrier recombination/transport/collection process. For details of the optoelectronic simulation, please refer to our previous reports on photodetectors and solar cells. ,, Here, we just show the core model describing the carrier dynamic behaviors: where J n ( J p ) is the total electron (hole) current density, q is the electron charge, Φ is the electrostatic potential, ε r is the material dielectric constant, n ( p ) is the electron (hole) concentration, N d ( N a ) the donor (acceptor) concentration, J n‑diff ( J n‑drif ) is the electron diffusion (drift) current density, J p‑diff ( J p‑drif ) is the hole diffusion (drift) current density, D n ( D p ) is the diffusion coefficient of electron (hole), μ n (μ p ) is the electron (hole) mobility, and U is the total bulk recombination rate, which is the sum of the Shockley-Read-Hall (SRH), radiative, and Auger recombination rate. The surface recombination with typical velocity of 1 × 10 4 cm/s is also considered in the model .…”

“…For details of the optoelectronic simulation, please refer to our previous reports on photodetectors and solar cells. 32,37,38 Here, we just show the core model describing the carrier dynamic behaviors:…”