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Sunday, July 15, 2018

#389 MOS potential barrier

In blogs # 382 and # 384 formation of the p-n junction and Schottky diodes were discussed as  two ways to form  potential barriers upon which operation of semiconductor devices is based. Actually, there is a third way, and pretty important one, although, it works in the device somewhat differently that p-n junction and Schottky contact.

The third way of potential barrier formation involves bringing semiconductor to contact with an insulator which results in the alteration of potential distribution in semiconductor in the region immediately adjacent to its interface with insulator. To convert such structure into a current controlling device metal contact (referred to as a gate) needs to be formed on the surface of an insulator making it into what is known as Metal-Insulator-Semiconductor, or MIS configuration; more commonly used is synonymous term Metal-Oxide-Semiconductor, or MOS.  Rings the bell? I am sure it does.


The difference between p-n junction and Schottky contact structures on one end and MOS devices on the other is in the direction of the current flow. In the former case current flows in the direction normal to the surface and potential barrier heights control the flow. In the case of the former, current flowing in the direction parallel to the surface can be controlled by altering distribution of the space-charge associated with the potential barrier.

Posted by Jerzy Ruzyllo at 11:22 AM | Semiconductors | Link is the personal blog of Jerzy Ruzyllo. With over 35 years of experience in academic research and teaching in the area of semiconductor engineering (currently holding position of a Distinguished Professor of Electrical Engineering and Professor of Materials Science and Engineering at Penn State University), he has a unique perspective on the developments in this progress driving technical domain and enjoys blogging about it.

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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