Date of Award

Summer 2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Electrical & Computer Engineering

Committee Director

Sacharia Albin

Committee Member

Sylvain Marsilac

Committee Member

Gon Namkoong

Committee Member

Ramjee Balasubramanian

Abstract

Diamond is the hardest bulk material with the highest thermal conductivity. It is also an excellent wide band gap material; hence, diamond is suitable for electronic, mechanical and biological applications. Unfortunately, natural diamond is prohibitively expensive for most technological applications. Polycrystalline diamond, with properties close to those of natural diamond, has been synthesized since the 1950s. Among many methods employed for diamond thin film synthesis, chemical vapor deposition (CVD) using microwave plasma (MW) is quite popular for several reasons. Well-confined plasma that does not touch the reaction chamber walls can be produced directly on the substrate. Hence, contamination in the grown films could be reduced to a minimum unlike in hot filament based CVD. Indirect substrate heating is also achieved by the microwave plasma. Diamond films and coatings have found wide range applications in sensors, protective coatings, and optical windows, electronic and electrochemical devices. Many such applications require patterning of diamond thin films. However, the unusual chemical inertness and hardness make patterning of diamond quite difficult. Reactive ion etching (RIE) is a common method for diamond patterning, but it involves reactive gas like SF6 and highly selective masking material such as gold. In addition, this process suffers from the problems of over-etching and micro-mask effect.

In this dissertation, a novel technique for patterning diamond thin films using selective nucleation and growth is presented in detail. Selective nucleation of diamond seeds is achieved by a first lift-off with acetone to remove the photo resist mask. Diamond thin film is then grown on a silicon wafer with silicon dioxide as the patterning mask. Silicon dioxide along with the diamond particles grown on top of it is removed by a second lift-off to obtain selective growth. Diamond patterns with resolution in micron range are achieved without dry etching. Diamond resistors and hetero-junction diamond/silicon diodes are fabricated using this technique. A rectifying ratio of two orders magnitude is achieved for the diodes. Quantitative Raman measurement using diamond as a reference is demonstrated. This simple selective nucleation growth technique can be applied to the fabrication of devices for many different applications.

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DOI

10.25777/ywbf-9c45

ISBN

9781267736468

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