Amorphous Silicon Resonators for Monolithic Light Emission

Solution Overview

Problem

Current silicon photonics technologies face challenges in realizing a monolithic integrated optical system with a light source, lightwave circuit, and detector on a single chip, as existing solutions involve costly heterogeneous integration of III-V materials, low manufacturing yields, and non-CMOS compatibility, with electrically pumped sources being multimode and not suitable for continuous wave operation.

Innovation Solution

The development of amorphous silicon devices and systems, including hydrogenated amorphous silicon (aSi:H) thin films deposited using low temperature plasma enhanced chemical vapor deposition (LT-PECVD), which create defects for enhanced spontaneous light emission and electroluminescence, integrated with crystalline silicon to form PIN junctions and resonators, enabling efficient light emission and detection at telecommunications wavelengths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If heterogeneous integration of III-V materials is used to create light sources, then light emission capability is improved, but manufacturing cost increases and manufacturing yield decreases

Engineering Contradiction:

Improvelight emission capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

Use of energy by moving objectVSEase of manufacture

Solution Approach 1:

The patent merges the light source and detector functions onto a single silicon chip by using hydrogenated amorphous silicon (a-Si:H) for light emission and crystalline silicon for detection, eliminating the need for separate III-V material integration and reducing manufacturing complexity

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The invention uses composite material structures including hydrogenated amorphous silicon layers integrated with crystalline silicon substrates, combining the light-emitting properties of a-Si:H with the detection capabilities of c-Si to create a monolithic device

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If heterogeneous integration of III-V materials is used to create light sources, then light emission capability is improved, but manufacturing yield decreases

Engineering Contradiction:

Improvelight emission capabilityVSAvoidmanufacturing yield

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent merges the light source and detector functions onto a single silicon chip by using hydrogenated amorphous silicon (a-Si:H) for light emission and crystalline silicon for detection, eliminating the need for separate III-V material integration and reducing manufacturing complexity

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The invention uses homogeneous silicon-based materials (amorphous and crystalline) throughout the device structure, ensuring consistent manufacturing processes and material properties that improve yield compared to heterogeneous material integration

Inventive Principle:

Principle #33Homogeneity

3Adaptability or versatility

If conventional silicon materials are used, then CMOS compatibility is achieved, but light emission at telecommunications wavelengths is not possible

Engineering Contradiction:

ImproveCMOS compatibilityVSAvoidlight emission capability

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the material phase parameter from crystalline to amorphous silicon, which fundamentally alters the optical properties to enable light emission at telecommunications wavelengths while maintaining CMOS processing compatibility

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses composite material structures including hydrogenated amorphous silicon layers integrated with crystalline silicon substrates, combining the light-emitting properties of a-Si:H with the detection capabilities of c-Si to create a monolithic device

Inventive Principle:

Principle #40Composite materials

4Use of energy by moving object

If electrically pumped sources are used, then light emission is achieved, but the sources are multimode and not suitable for continuous wave operation

Engineering Contradiction:

Improvelight emission capabilityVSAvoidemission mode control

Core Design Contradiction:

Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The patent applies local quality enhancement by introducing hydrogenated amorphous silicon layers with specific defect structures at targeted locations within the silicon chip, creating localized emission regions that support single-mode operation

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the material phase parameter from crystalline to amorphous silicon, which fundamentally alters the optical properties to enable light emission at telecommunications wavelengths while maintaining CMOS processing compatibility

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 enables efficient, CMOS-compatible, and cost-effective monolithic integration of light sources and detectors on a silicon chip, achieving significant luminescence quantum yield and electroluminescence at telecommunications wavelengths, overcoming the limitations of existing silicon photonics technologies.

Implementation Method 1

experimental results that demonstrate light emission at telecommunications wavelengths from amorphous silicon resonators

Methodology Applied

Scientific EffectSpontaneous emission: Luminescence

Implementation Method 2

Resonators patterned in the thin films enhance luminescence by the Purcell effect, which is the increase in spontaneous emission rate proportional to the ratio of resonator quality factor to mode volume (Q/V)

Methodology Applied

Scientific EffectPurcell effect:

Implementation Method 3

aSi:H PIN junction devices for on-chip light generation and detection

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 4

Optical resonators or cavities localize light at specific resonant wavelengths depending on the resonator geometry

Methodology Applied

Scientific EffectResonance: Resonance

Implementation Method 5

Photons are guided on a planar chip by integrated photonic waveguides

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 6

high-speed electrical-to-optical and optical-to-electrical converters

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS10418238B2Devices, systems, and methods for light emission and detection using amorphous silicon

Publication Date: 2019.09.17 OHIO STATE INNOVATION FOUND

AI summary

Amorphous silicon devices, systems, and related methods are described herein. An example method for fabricating a thin film with light-emitting or light-detecting capability can include depositing a thin film of amorphous silicon on a wafer such that crystalline defects are distributed throughout the thin film. Additionally, an example photonic device can include a p-doped region and an n-doped region formed on a wafer, and a resonator structure formed on the wafer. The resonator structure can be formed from amorphous silicon and can be arranged between the p-doped and n-doped regions to form a PIN junction. Optionally, the photonic device can be incorporated into a monolithic integrated optical system.