Related Experiment Video
Updated: Sep 20, 2025

Electric-field Control of Electronic States in WS2 Nanodevices by Electrolyte Gating
Published on: April 12, 2018
Achieving High Current Stability of Gated Carbon Nanotube Cold Cathode Electron Source Using IGBT Modulation for
Yajie Guo1, Junfan Wang1, Baohong Li1
1State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China.
A novel gated carbon nanotube cold cathode electron gun, modulated by Insulated Gate Bipolar Transistor (IGBT), achieves high current stability for X-ray radiotherapy applications, ensuring consistent dose delivery.
Area of Science:
- Materials Science
- Physics
- Medical Physics
Background:
- Radiotherapy requires stable X-ray dose delivery, posing a challenge for conventional cold cathode X-ray sources.
- Carbon nanotube (CNT) cold cathodes offer potential for high-performance electron emission but require stable current control.
Purpose of the Study:
- To develop a gated carbon nanotube cold cathode electron gun with enhanced current stability.
- To investigate the application of this electron gun in a stable X-ray source for radiotherapy.
Main Methods:
- Fabrication of CNT films on stainless steel substrates via chemical vapor deposition.
- Assembly of CNT films into a gated electron gun with control and focus electrodes.
- Implementation of Insulated Gate Bipolar Transistor (IGBT) modulation for cathode current stabilization.
Main Results:
- Achieved a maximum cathode current of 200 μA with a 53% transmission rate.
- Demonstrated high cathode current stability (<0.5% fluctuation) over 50 minutes of continuous operation using IGBT modulation.
- Obtained a stable X-ray dose rate when the electron gun was integrated into a transmission target X-ray source.
Conclusions:
- The developed gated carbon nanotube cold cathode electron gun exhibits excellent current stability.
- IGBT modulation is an effective technique for stabilizing CNT cold cathode electron emission.
- This technology shows significant feasibility for creating stable X-ray sources applicable to radiotherapy.
Related Concept Videos
MOSFET: Enhancement Mode
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...
MOSFET Amplifiers
Characteristics of MOSFET
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...
Biasing of FET
In an N-channel JFET, the structure consists of N-type material forming the channel on a P-type substrate, with the...
Biasing of Metal-Semiconductor Junctions
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...
MOSFET: Depletion Mode
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...

