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Sunday, August 29, 2021

#477 MIS tunnel junction diode

As discussed in my Guide to Semiconductor Engineering (see also here), operation of two-terminal semiconductor device is based on the ability to control the current flowing across it by either varying concentration of free charge carriers available for conduction (resistors), or by creating a potential barrier height of which depends on the applied voltage and affects the flow of charge carriers (diodes). 


The potential barrier needed to make an active two-terminal semiconductor device is commonly obtained either by the formation of the p-n junction (p-n junction diode), or by bringing to contact properly selected metal and semiconductor (metal-semiconductor, or M-S junction also known as Schottky diode).  


The third option involves structures in which metal and semiconductor are separated by ultrathin (in a thickness range of 3 nm) layer of insulator, typically an oxide. Because of its limited thickness, and under proper bias conditions, current can flow between metal and semiconductor by electrons tunneling across the oxide. Just like in the case of p-n junction and Schottky contacts, density of such current depends on the direction of the applied voltage. Devices of this type are referred to as MIS (Metal-Insulator-Semiconductor) tunnel junction diodes, or MIS tunnel diodes in short.  


MIS tunnel diodes are rarely used in the implementation of practical devices mainly because p-n junction and Schottky diodes are successfully fulfilling their roles. However, there are situations in which whether because of the limited thermal stability of semiconductor material, its geometry, or lack of metals forming Schottky contacts on its surface, MIS tunnel diode configuration as a potential barrier contriling structure may come useful. This usefulness extends into transistor technology and leads to the MIS Tunnel Transistor to be briefly introduced next time.

Posted by Jerzy Ruzyllo at 05:08 PM | Semiconductors | Link is a personal blog of Jerzy Ruzyllo. He is Distinguished Professor Emeritus in the Department of Electrical Engineering at Penn State University. With over forty years' experience in academic research and teaching in semiconductor engineering he has a unique perspective on the developments in this technical domain and enjoys blogging about it.

This book gives a complete account of semiconductor engineering covering semiconductor properties, semiconductor materials, semiconductor devices and their uses, process technology, fabrication processes, and semiconductor materials and process characterization.

With over 2000 terms defined and explained, Semiconductor Glossary is the most complete reference in the field of semiconductors on the market today.


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