Photonic Crystal Fabrication via Selective Epitaxy
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Solution Overview
Problem
Photonic crystal-based devices face challenges in electrical actuation, particularly in efficiently injecting carriers into the active region without causing excessive absorption losses and precise placement of active material within the cavity.
Innovation Solution
A method for fabricating semiconductor structures involves creating a photonic crystal structure with selective epitaxy, replacing the first material in the central part with optically active materials, and using epitaxial in-plane lateral doping to form p-i-n structures, allowing for efficient carrier confinement and precise placement of gain material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the photonic cavity is implemented in the active material, then strong light-matter interaction is achieved, but excessive absorption losses occur because light is absorbed outside of the cavity
Solution Approach 1:
The device is divided into two distinct material regions: a photonic cavity made of low-loss material (e.g., silicon nitride) and an active material region (e.g., quantum wells) for carrier injection. This segmentation allows the cavity to confine light with minimal absorption while the active material provides gain only where needed, resolving the contradiction between light-matter interaction and absorption losses.
Solution Approach 2:
The active material is selectively placed only in specific regions where carrier injection is required, rather than throughout the entire cavity. This local quality approach ensures that light-matter interaction occurs precisely where needed while minimizing absorption losses in other parts of the cavity structure.
2Reliability
If the active material is placed in the central part of the cavity, then carrier confinement is improved, but precise placement remains a difficult challenge
Solution Approach 1:
The photonic cavity structure is fabricated first with precisely defined geometric features that serve as templates. The active material is then deposited or integrated into predetermined locations within this pre-fabricated cavity, ensuring accurate placement without requiring complex alignment steps during active material integration.
Solution Approach 2:
The photonic cavity structure itself acts as an intermediary that guides and confines both light and carriers. By designing the cavity geometry to naturally confine carriers in its central region, the structure serves as a mediator that achieves precise effective placement of active material functionality without requiring ultra-precise manufacturing of the active material position itself.
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 enhances device performance by reducing absorption losses and improving light-matter interaction, enabling high-speed modulation and threshold-less laser behavior.
Implementation Method 1
Photonic crystal nanocavities are ideal platforms for such semiconductor light sources as they may provide strong light-matter interaction, high Q/V ratios
Implementation Method 2
replacing the first material within the predefined part of the photonic crystal structure with one or more second materials by selective epitaxy
Implementation Method 3
A challenge in photonic cavity-based devices is electrical actuation, i.e. to inject carriers efficiently to the active region
Data Source
AI summary
The invention relates to a method for fabricating a semiconductor structure. The method comprises fabricating a photonic crystal structure of a first material, in particular a first semiconductor material and selectively removing the first material within a predefined part of the photonic crystal structure. The method further comprises replacing the first material within the predefined part of the photonic crystal structure with one or more second materials by selective epitaxy. The one or more second materials may be in particular semiconductor materials. The invention further relates to devices obtainable by such a method.