Harvard College

Changhyun Ko

Shriram Ramanathan

Dmitry Ruzmetov

Venkatesh Narayanamurti

Phase transition devices may include a functional layer made of functional material that can undergo a change in conductance in response to an external stimulus such as an electric or magnetic or optical field, or heat. The functional material transitions between a conducting state and a non-conducting state, upon application of the external stimulus. A capacitive device may include a functional layer between a top electrode and a bottom electrode, and a dielectric layer between the functional layer and the top electrode. A three terminal phase transition switch may include a functional layer, for example a conductive oxide channel, deposited between a source and a drain, and a gate dielectric layer and a gate electrode deposited on the functional layer. An array of phase transition switches and/or capacitive devices may be formed on a substrate, which may be made of inexpensive flexible material.

Phase transition devices and smart capacitive devices

Thin films of vanadium oxide having exceptionally high metal-insulator transition properties are synthesized by RF sputtering. An Al2O3 substrate is placed in a sputtering chamber and heated to a temperature up to about 550 degrees Celsius. Ar and O2 gases are introduced into the sputtering chamber at the flow values of about 92.2 sccm and about 7.8 sccm respectively. A voltage is applied to create a plasma in the chamber. A sputtering gun with vanadium target material is ignited and kept at a power of about 250 W. The phase transition parameters of vanadium dioxide thin films, synthesized by RF sputtering, are modulated by exposing the vanadium dioxide thin film to UV (ultraviolet) radiation so as to induce a change in oxygen incorporation of the vanadium dioxide thin film.

Growing community of inventors

Cambridge, MA, United States of America

Changhyun Ko