Graphene Waveguide Photodetector Without Transfer-Related Defects
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Solution Overview
Problem
Current methods for manufacturing graphene-based photodetectors and electro-optic modulators face challenges in achieving reliable and consistent production for commercial scale, particularly due to issues with graphene transfer processes that result in contamination, damage, and reduced quality, hindering the delivery of graphene's unique properties.
Innovation Solution
A photodetector and electro-optic modulator system is developed using a graphene layer grown by chemical vapor deposition (CVD) on a substrate with a silicon nitride and/or oxide insulative layer, featuring a patterned graphene monolayer with ohmic contacts, and an integrated system for optical transmission that shares a common waveguide or substrate, enabling high-quality graphene growth directly on the substrate without transfer-related defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If graphene transfer processes are used to manufacture photodetectors, then graphene can be applied over waveguide structures, but contamination and damage occur resulting in reduced quality and reliability
Solution Approach 1:
The patent removes the problematic transfer step from the manufacturing process by growing graphene directly on the waveguide substrate using CVD. This extraction of the transfer process eliminates the source of contamination and damage while still achieving the goal of applying graphene to the waveguide structure.
Solution Approach 2:
The patent performs preliminary surface preparation of the substrate (cleaning, oxidation, or plasma treatment) before growing graphene directly on it. This preliminary action ensures the substrate surface is ready for direct graphene growth, eliminating the need for subsequent transfer operations that cause contamination.
2Ease of manufacture
If graphene transfer processes are used, then graphene can be positioned on waveguides, but manufacturing consistency and reliability for commercial scale production are hindered
Solution Approach 1:
The transfer process is completely removed from the manufacturing workflow. Graphene is grown directly on the substrate in a CVD reactor, enabling scalable production without the inconsistent and time-consuming transfer steps that prevent commercial scale manufacturing.
Solution Approach 2:
The substrate undergoes preliminary surface treatment (oxidation, plasma, or chemical cleaning) before graphene growth to ensure optimal growth conditions. This preliminary preparation enables consistent, high-quality graphene formation across large substrate areas suitable for commercial production.
3Reliability
If direct CVD growth of graphene is performed on substrate, then transfer-related contamination and damage are avoided, but process conditions must be precisely controlled for high-quality growth
Solution Approach 1:
The substrate undergoes preliminary surface treatment (oxidation, plasma, or chemical cleaning) before graphene growth to create an optimal surface for CVD. This preliminary action reduces the complexity of controlling growth conditions by pre-preparing the surface to promote uniform, high-quality graphene formation.
Solution Approach 2:
The patent uses an intermediary layer or surface treatment (such as oxide layers or plasma-treated surfaces) between the substrate and graphene to facilitate controlled growth. This intermediary enables reliable high-quality growth by mediating the interaction between substrate and carbon precursors during CVD.
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 results in improved carrier mobility, reduced energy consumption, and enhanced performance by avoiding transfer-related contamination and damage, allowing for the effective integration of graphene's unique properties into commercial photonic devices with increased reliability and consistency.
Implementation Method 1
a first insulative layer on and across an upper surface of the substrate and waveguide material wherein the first insulative layer comprises silicon nitride and/or an oxide of one or more of aluminium, hafnium and magnesium
Implementation Method 2
forming a graphene layer arranged on the first insulative layer and over the first channel of waveguide material
Implementation Method 3
at least two ohmic contacts, each provided in contact with the graphene layer and arranged on either side of the first channel of waveguide material
Implementation Method 4
a first channel of waveguide material embedded in the substrate wherein the substrate and the waveguide material together provide a substantially flat upper surface
Data Source
AI summary
There is provided a photodetector comprising: a substrate having a first channel of waveguide material embedded therein, the substrate and the waveguide material together providing a substantially flat upper surface: a first insulative layer on and across the upper surface: a graphene layer arranged on the first insulative layer and over the first channel of waveguide material: and at least two ohmic contacts, each provided in contact with the graphene layer and arranged on either side of the first channel of waveguide material: wherein the first insulative layer comprises silicon nitride and/or an oxide of one or more of aluminium, hafnium and magnesium.