Diamond Semiconductor Element Defect Reduction via Surface Orientation

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Solution Overview

Problem

Diamond semiconductor elements face challenges due to high crystal defects, which hinder the realization of their potential high thermal conductivity, high breakdown electric field strength, and high-frequency characteristics, making it difficult to produce practical transistors with improved transconductance and oscillation frequency.

Innovation Solution

The solution involves shifting the surface orientation of diamond substrates slightly from the [001] direction to reduce crystal defects, optimizing electrode distances and thicknesses, and using high-pressure and high-temperature annealing to improve diamond thin-film quality, while also employing specific dopant elements and ion implantation techniques to achieve the required hole concentration and dopant atom concentration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If diamond single-crystal is used for semiconductor elements, then high thermal conductivity and high breakdown electric field strength are achieved, but extremely high density of crystal defects occurs

Engineering Contradiction:

Improvebreakdown electric field strengthVSAvoidcrystal defect density

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent changes the surface orientation parameter of the diamond substrate from the conventional [001] direction to the <110> direction. This parameter change fundamentally alters the crystal growth characteristics and defect formation mechanisms, reducing crystal defect density while maintaining the inherent high breakdown electric field strength of diamond material

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If surface orientation is precisely in the [001] direction, then conventional transistor structure can be formed, but crystal defects occur at extremely high density

Engineering Contradiction:

Improvetransistor structure formationVSAvoidcrystal defect density

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent modifies the surface orientation parameter from [001] to <110>, which changes the atomic arrangement and surface morphology. This enables alternative transistor structure configurations that are compatible with the new orientation while dramatically reducing crystal defect density during growth

Inventive Principle:

Principle #35Parameter changes

3Speed

If diamond semiconductor is used for high-frequency applications, then high carrier mobility and saturated velocity are achieved, but crystal defects hinder performance realization

Engineering Contradiction:

Improvecarrier mobilityVSAvoidcrystal defect density

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

By changing the surface orientation to <110>, the patent optimizes the crystal growth conditions and reduces defect formation. This allows the high carrier mobility and saturated velocity properties of diamond to be fully realized without being hindered by crystal defects

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach significantly reduces crystal defects, enhances transconductance, increases the maximum oscillation frequency, and achieves a practically useful diamond semiconductor with improved thermal and electrical properties, enabling high-power and high-frequency applications.

Implementation Method 1

A diamond has the highest thermal conductivity among a variety of materials

Methodology Applied

Scientific EffectThermal conductivity: Conduction (thermal)

Implementation Method 2

has the highest breakdown electric field strength among semiconductors

Methodology Applied

Scientific EffectBreakdown electric field: Electric Field

Implementation Method 3

Since holes and electrons in the diamond have a high mobility and saturated velocity

Methodology Applied

Scientific EffectCarrier mobility: Conduction (electrical)

Data Source

PatentUS8487319B2Diamond semiconductor element and process for producing the same

Publication Date: 2013.07.16 NIPPON TELEGRAPH & TELEPHONE CORP

AI summary

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.