Nanoscale Vacuum Diode Based on Thermionic Emission for High Temperature Operation

• Main Authors: Zhihua Shen, Qiaoning Li, Xiao Wang, Jinshou Tian, Shengli Wu
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: Micromachines
• Subjects: finite integration technique (FIT); thermionic emission; nanoscale vacuum diode; space-charge limited (SCL) current
• Online Access: https://www.mdpi.com/2072-666X/12/7/729

Vacuum diodes, based on field emission mechanisms, demonstrate a superior performance in high-temperature operations compared to solid-state devices. However, when considering low operating voltage and continuous miniaturization, the cathode is usually made into a tip structure and the gap between cathode and anode is reduced to a nanoscale. This greatly increases the difficulty of preparation and makes it difficult to ensure fabrication consistency. Here, a metal-insulator-semiconductor (MIS) structural nanoscale vacuum diode, based on thermionic emission, was numerically studied. The results indicate that this device can operate at a stable level in a wide range of temperatures, at around 600 degrees Kelvin above 260 K at 0.2 V voltage bias. Moreover, unlike the conventional vacuum diodes working in field emission regime where the emission current is extremely sensitive to the gap-width between the cathode and the anode, the emission current of the proposed diode shows a weak correlation to the gap-width. These features make this diode a promising alternative to vacuum electronics for large-scale production and harsh environmental applications.