Diamond semiconductor element and process for producing the same

Abstract

An integrated optical waveguide has a first optical waveguide, a second optical waveguide, and a groove. The second optical waveguide is coupled to the first optical waveguide and has a refractive index that is different from the first optical waveguide. The groove is disposed so as to traverse an optical path of the first optical waveguide and is separated from an interface between the first optical waveguide and the second optical waveguide by a predetermined spacing. The spacing from the interface and the width of the groove are determined such that reflection at a boundary between the first optical waveguide and the second optical waveguide is weakened. A semiconductor board may be disposed at a boundary between the first optical waveguide and the second optical waveguide. In this case, the width of the groove and the thickness of the semiconductor board are determined such that light reflected off an interface between the first optical waveguide and the groove is weakened by light reflected from an interface between the groove and the semiconductor board, and by light reflected from an interface between the semiconductor board and the second optical waveguide.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a divisional of U.S. patent application Ser. No. 11 / 577,678, filed Apr. 20, 2007, which is a nationalization of PCT Application No. PCT / JP2006 / 312334, filed Jun. 20, 2006, which claims priority to Japanese Patent Application Nos. 2005-179751 filed Jun. 20, 2005, 2005-270541 filed Sep. 16, 2005, 2005-307231 filed Oct. 21, 2005, and 2006-061838 filed Mar. 7, 2006, which are incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention relates to a diamond semiconductor element, and more particularly, to a semiconductor element structure in which occurrence of a crystal defect peculiar to a diamond semiconductor element is suppressed, and a process for producing the same.BACKGROUND ART[0003]A diamond has the highest thermal conductivity among a variety of materials, and has the highest breakdown electric field strength among semiconductors. Accordingly, the diamond is the semiconductor material most s...

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Benefits of technology

001] direction, thereby making it possible to significantly reduce the occurrence of crystal...

Problems solved by technology

However, a diamond single-crystal has the problem of an extremely high density of a crystal defect as compared with that of another semiconductor, for example, silicone, gallium arsenide, indium phosphide, gallium nitride, and the like.

The diamond semiconductor has the physically derived limitation that the channels in which the electron and the hole of a transistor travel are required to be located within 0.1 μm from the surface unlike other semiconductors, for example, silicone, gallium arsenide, indium, gallium nitride, and the like (see non-patent document 3).

This presents fewer problems in the cases of other semiconductors, but in the diamond semiconductor element this is a critical problem resulting from its physical properties that needs to be solved.

In other words, the conventional art is incapable of simultaneously satisfying the two requirements, “a reduction in the source-gate electrode distance and the gate-drain electrode distance” and “an increase in the thickness of the source electrode and the thickness of the drain electrode”.

However, impurities and a large number of crystal defects such as a growth hillock, abnormal growth particles and the like exist in the above diamond single-crystal thin-film.

However, in non-patent document 5, if the temperature is increased for an improvement in crystallinity, when the temperature reaches a certain degree (1200° C.) or more, the conversion to graphite progresses in the diamond thin-film, resulting in an increase in deterioration in crystallinity.

Also, since a p-type semiconductor la...

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