Compensated Photonic Device Interface for Low Carrier Concentration

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Solution Overview

Problem

Photonic devices with multiple materials/layers, such as Ge-on-Si or GaAs-on-Si photodiodes, suffer from defects and dislocations at material interfaces, leading to high carrier concentrations that require higher bias voltages for operation, causing leakage currents and limiting high-speed device performance.

Innovation Solution

A compensated photonic device structure with a compensation region doped with specific dopants at the interface between the substrate and functional layer, reducing carrier concentrations by up to 50% compared to non-compensated devices, utilizing silicon-based substrates and germanium or gallium arsenide functional layers with lattice mismatches greater than 1%.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple materials with different lattice constants are used to create photonic devices, then device functionality is improved, but defect-induced carrier concentration increases

Engineering Contradiction:

Improvedevice functionalityVSAvoidcarrier concentration

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent introduces a compensation region with opposite polarity dopants to convert the harmful effect of defect-induced carriers into a beneficial neutralization. The compensation region creates carriers of opposite polarity that neutralize the defect-induced carriers, transforming the harmful high carrier concentration into a controlled and compensated state, enabling functional heteromaterial devices while maintaining low effective carrier concentrations.

Inventive Principle:

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

Solution Approach 2:

The patent applies local quality by creating a compensation region with specific dopant characteristics at the interface between heteromaterials, while keeping other regions of the device with their original doping profiles. This localized compensation approach targets only the problematic interface region where lattice mismatch occurs, leaving the rest of the device structure unchanged and maintaining its original functionality.

Inventive Principle:

Principle #3Local quality

2Ease of operation

If higher bias voltage is applied to overcome defect-induced carrier concentration, then photodiode operation is enabled, but leakage current increases

Engineering Contradiction:

Improvephotodiode operationVSAvoidleakage current

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The compensation region converts the harmful high carrier concentration at the interface into a beneficial neutralized state by introducing opposite polarity dopants. This neutralization reduces the effective carrier concentration, allowing the photodiode to operate at lower bias voltages without requiring high fields that would generate excessive leakage current, thus transforming the operational challenge into a solution.

Inventive Principle:

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

3Ease of operation

If higher bias voltage is applied for photodiode operation, then carrier depletion is achieved, but device speed performance deteriorates

Engineering Contradiction:

Improvecarrier depletionVSAvoiddevice operating speed

Core Design Contradiction:

Ease of operationVSSpeed

Solution Approach 1:

The compensation region neutralizes defect-induced carriers, transforming the harmful high carrier concentration into a beneficial low effective carrier concentration state. This enables efficient carrier depletion at lower bias voltages, allowing high-speed operation (25 GHz or beyond) without the performance degradation that would result from applying high bias voltages to overcome defect-induced carriers.

Inventive Principle:

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

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 compensation region effectively reduces defect-induced carrier concentrations, enabling lower bias voltages and reduced leakage currents, thus enhancing the performance of high-speed photonic devices by maintaining carrier concentration levels 50% or less than non-compensated devices.

Implementation Method 1

The compensation region may be doped with compensation dopants such that a first carrier concentration (caused by defects) around the interface region of the function layer is reduced and a second carrier concentration (caused by defects) in a bulk region of the functional layer is reduced.

Methodology Applied

Scientific EffectDoping: Dopants

Data Source

PatentUS10340409B2Compensated photonic device structure and fabrication method thereof

Publication Date: 2019.07.02 SIFOTONICS TECH CO LTD

AI summary

Various embodiments of a compensated photonic device structure and fabrication method thereof are described herein. In one aspect, a photonic device may include a substrate and a functional layer disposed on the substrate. The substrate may be made of a first material and the functional layer may be made of a second material that is different from the first material. The photonic device may also include a compensation region formed at an interface region between the substrate and the functional layer. The compensation region may be doped with compensation dopants such that a first carrier concentration around the interface region of function layer is reduced and a second carrier concentration in a bulk region of functional layer is reduced.