Schottky Junction Photodetector Using Germanium Annulus

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Solution Overview

Problem

Conventional photodetectors for mid-infrared and long wavelength infrared regimes face performance limitations due to parasitic hot electron processes and require high-cost, toxic mercury cadmium telluride (MCT) materials, which are difficult to integrate with CMOS fabrication processes and pose environmental concerns.

Innovation Solution

A photodetector design featuring a semiconductor substrate with a semiconductor annulus and a metal layer forming a Schottky junction, where the metal layer surrounds and fills the annulus, enabling efficient hot electron capture and conversion of photons to electrical current using CMOS-compatible materials and processes, avoiding the use of MCT.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If MCT material is used for detecting low-energy photons in long wavelength infrared regime, then detection capability is improved, but manufacturing cost increases and integration with CMOS processes becomes difficult

Engineering Contradiction:

Improvedetection capabilityVSAvoidmanufacturing cost and integration

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the material parameter from MCT to germanium semiconductor with metal Schottky junction, enabling detection of long wavelength infrared photons while maintaining CMOS compatibility and reducing manufacturing cost

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces expensive MCT material with cheaper germanium semiconductor that can be fabricated using standard CMOS processes, making the detector more cost-effective

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If MCT material is used for infrared detection, then detection performance is improved, but environmental pollution increases due to toxicity

Engineering Contradiction:

Improvedetection performanceVSAvoidenvironmental pollution

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces toxic MCT material with environmentally friendly germanium semiconductor, eliminating pollution concerns while maintaining detection performance

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent converts the harmful toxic property of MCT into a benefit by selecting germanium material that is non-toxic and environmentally safe, turning a negative attribute into a positive one

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Productivity

If conventional photoexcitation and non-radiative decay processes are used, then carrier generation occurs, but hot electron parasitic processes limit device performance

Engineering Contradiction:

Improvecarrier generationVSAvoidhot electron parasitic loss

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent converts the harmful hot electron parasitic process into a beneficial detection mechanism by using metal Schottky junctions to generate hot electrons through photon absorption, which then provide the detection signal

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent replaces the conventional semiconductor photoexcitation mechanism with a metal-semiconductor Schottky junction mechanism, where hot electron generation at the interface becomes the primary detection mechanism, substituting the traditional approach with a new physical mechanism

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

The solution provides efficient detection of infrared radiation across mid and long wavelength spectra, is tunable for specific wavelength bands, and is fabricated using environmentally friendly, cost-effective CMOS-compatible materials and processes, overcoming the limitations of traditional MCT-based detectors.

Implementation Method 1

the metal layer in the first region forms a Schottky junction with the semiconductor ring

Methodology Applied

Scientific EffectSchottky junction:

Implementation Method 2

enabling efficient hot electron capture and conversion of photons to electrical current

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS11688820B2Photodetectors

Publication Date: 2023.06.27 REGENTS OF THE UNIVERSITY OF MINNESOTA

AI summary

The subject matter of this specification can be embodied in, among other things, a photodetector that includes a semiconductor substrate, a semiconductor annulus on a planar face of the semiconductor substrate, and a metal layer on the semiconductor substrate, wherein the metal layer comprises a first region surrounding the semiconductor annulus and comprises a second region filling an interior region to the semiconductor annulus, and the metal layer in the first region forms a Schottky junction with the semiconductor ring.