Optogenetic Device with ZrB2 Buffer and Glass-Like Carbon Electrodes
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Solution Overview
Problem
Semiconductor structures with group III nitrides formed on silicon substrates are complicated and expensive to fabricate, and result in less efficient light-emitting optoelectronic devices due to silicon's high UV absorption, while those formed on sapphire substrates face lattice mismatch and thermal expansion issues, leading to dislocation density and morphological problems.
Innovation Solution
The development of an integrated optogenetic device with group III nitride materials formed on a sapphire substrate using a ZrB2 buffer layer, which provides a lattice-matched template for GaN growth, combined with glass-like carbon electrodes to create a stable structure for both neural stimulation and neurochemical recording, avoiding high temperature anneals that cause delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If group III nitride structures are formed on silicon substrates, then fabrication complexity and cost are reduced, but light-emitting efficiency decreases due to silicon's high UV absorption
Solution Approach 1:
The patent introduces a buffer layer as an intermediary between the silicon substrate and the group III nitride layer. This buffer layer mediates the interaction between silicon and GaN, reducing the harmful effects of silicon's UV absorption while maintaining the ease of silicon substrate fabrication. The buffer layer acts as a transition zone that improves light-emitting efficiency without sacrificing manufacturing simplicity.
2Loss of energy
If group III nitride structures are formed on sapphire substrates, then light-emitting efficiency is improved, but lattice mismatch and thermal expansion issues cause dislocation density and morphological problems
Solution Approach 1:
The buffer layer serves as an intermediary that gradually transitions from the sapphire substrate to the GaN layer, reducing the abrupt lattice mismatch. This gradual transition minimizes dislocation density and morphological issues while preserving the high light-emitting efficiency advantage of sapphire substrates.
Solution Approach 2:
The buffer layer enables gradual parameter changes in lattice constant and thermal expansion coefficient from the sapphire substrate to the GaN layer. This gradual parameter transition reduces stress and dislocation formation, improving manufacturing precision while maintaining the optical benefits of sapphire.
3Reliability
If high temperature anneals are applied to form glass-like carbon electrodes, then electrode quality is improved, but delamination occurs due to thermal expansion mismatch
Solution Approach 1:
The patent employs a controlled annealing process with optimized temperature parameters that achieve sufficient electrode quality without exceeding the threshold that causes delamination. By carefully controlling the thermal parameter, the process maintains structural stability while producing high-quality glass-like carbon electrodes.
Solution Approach 2:
The buffer layer acts as a cushioning layer that accommodates thermal expansion differences during the annealing process. This pre-established buffer structure prevents delamination by absorbing the thermal stress before it reaches the electrode-substrate interface, allowing high-temperature processing without compromising structural stability.
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 a high-performance integrated optogenetic device capable of efficient neural stimulation and recording, with reduced dislocation density and morphological issues, enabling precise control of neural activities and neurochemical measurements.
Implementation Method 1
The first contact layer is further configured to be substantially lattice matched with the substrate layer and a bottom layer of the LED structure
Implementation Method 2
stimulating the sample of fluid by a light-emitting diode (LED) structure of the integrated optogenetic device
Implementation Method 3
an electrode that is configured to generate an electrical current based on a detection or measurement of one or more chemical component
Data Source
AI summary
Embodiments of the invention are directed to an integrated optogenetic device. The integrated optogenetic includes a substrate layer having a first substrate region and a second substrate region. The device further includes a first contact formed over the substrate layer in the first substrate region and a second contact layer formed over the substrate layer in the second region. In addition, the device includes a light-emitting diode (LED) structure communicatively coupled to the first contact layer and a biosensor element communicatively coupled to the second contact layer. The first contact layer is configured to operate as a bottom contact that provides electrical contact to the LED structure. The first contact layer is further configured to be substantially lattice matched with the substrate layer and a bottom layer of the LED structure.