Related Experiment Video
Updated: Apr 21, 2026
08:12
Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures
Published on: December 5, 2015
11.3K
Trion-induced negative photoconductivity in monolayer MoS2
C H Lui1, A J Frenzel2, D V Pilon1
1Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Physical Review Letters
|November 1, 2014
Summary
In doped monolayer molybdenum disulfide (MoS2), optical excitation unexpectedly decreased conductivity. This occurred due to photoexcited carriers forming trions, which increased effective mass and reduced electrical conduction.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Optoelectronics
Background:
- Optical excitation usually increases semiconductor conductivity.
- Monolayer molybdenum disulfide (MoS2) is a 2D semiconductor with unique electronic properties.
Purpose of the Study:
- Investigate the effect of optical excitation on conductivity in doped MoS2.
- Understand the underlying mechanisms of observed conductivity changes.
Main Methods:
- Ultrafast optical-pump terahertz-probe spectroscopy.
- Utilized doped monolayer molybdenum disulfide (MoS2) as the material system.
Main Results:
- Observed a significant transient decrease in conductivity upon optical excitation.
- Conductivity reduced to 30% of equilibrium value at high pump fluence.
- Identified trion formation (bound electron-hole states) as the cause.
Conclusions:
- Photoexcited carriers interacting with doping-induced charges form trions.
- Increased carrier effective mass due to trions leads to reduced conductivity.
- Demonstrates anomalous optical-electrical behavior in 2D materials driven by many-body interactions.
Related Concept Videos
01:25MOS Capacitor
1.8K
A Metal-Oxide-Semiconductor (MOS) capacitor is a fundamental structure used extensively in semiconductor device technology, particularly in the fabrication of integrated circuits and MOSFETs (metal-oxide-semiconductor field-effect transistors). The MOS capacitor consists of three layers: a metal gate, a dielectric oxide, and a semiconductor substrate.
The metal gate is typically made from highly conductive materials such as aluminum or polysilicon. Beneath the metal gate lies a thin layer of...
The metal gate is typically made from highly conductive materials such as aluminum or polysilicon. Beneath the metal gate lies a thin layer of...
1.8K
01:20MOSFET: Depletion Mode
1.2K
Depletion-mode MOSFETs represent a unique subset of MOSFET technology, functioning fundamentally differently from their enhancement-mode counterparts. Unlike enhancement MOSFETs, which require a positive gate-source voltage (Vgs) to turn on, depletion-mode MOSFETs are inherently conductive and "normally on" devices.
The primary characteristic of depletion-mode MOSFETs is their ability to conduct current between the drain and source terminals without gate bias. This inherent conductivity...
The primary characteristic of depletion-mode MOSFETs is their ability to conduct current between the drain and source terminals without gate bias. This inherent conductivity...
1.2K
01:17Characteristics of MOSFET
1.4K
Metal-oxide-semiconductor field-effect Transistors, or MOSFETs, play a critical role in electronic circuits. They are primarily utilized for amplifying and switching signals.
Various vital parameters influence their functionality, which is crucial for theory and electronics applications. First, channel dimensions, precisely length, and width, are pivotal. The size of these channels affects the transistor's ability to carry current and switching speeds; shorter channels typically enable...
Various vital parameters influence their functionality, which is crucial for theory and electronics applications. First, channel dimensions, precisely length, and width, are pivotal. The size of these channels affects the transistor's ability to carry current and switching speeds; shorter channels typically enable...
1.4K
01:22MOSFET: Enhancement Mode
1.1K
Enhancement-mode MOSFETs are pivotal components in electronics, distinguished by their capacity to act as highly efficient switches. They are part of the larger family of metal-oxide Semiconductor Field-Effect Transistors (MOSFETs). They are available in two types: p-channel and n-channel, each tailored to specific polarity operations.
In their basic form, enhancement-mode MOSFETs are typically non-conductive when the gate-source voltage (Vgs) is zero. This default 'off' state means no...
In their basic form, enhancement-mode MOSFETs are typically non-conductive when the gate-source voltage (Vgs) is zero. This default 'off' state means no...
1.1K
01:16MOSFET
1.8K
The Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) plays a pivotal role in modern electronics thanks to its versatility and efficiency in controlling electrical currents. This device, also known as IGFET, MISFET, and MOSFET, has three main terminals: the Source, Drain, and Gate. MOSFETs are classified into n-channel or p-channel types based on the doping characteristics of their substrate and the source or drain regions.
In an n-MOSFET, the structure includes n-type source and drain...
In an n-MOSFET, the structure includes n-type source and drain...
1.8K