Multi-Emitter Laser Diode Transfer to Reduce GaN Substrate Cost
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Solution Overview
Problem
Current blue and green laser diode technologies face inefficiencies, high costs, and limitations due to the use of costly free-standing GaN substrates and challenges in modulating at high speeds, with existing solutions like diode-pumped solid state lasers being sensitive to temperature and having high system costs.
Innovation Solution
A method for fabricating gallium and nitrogen-containing laser diodes using epitaxial deposition and transfer to a carrier wafer, allowing for the production of low-cost blue-light emitting GaN-based laser devices with reduced substrate costs by expanding the epitaxial material pitch, enabling efficient packaging and integration into various applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If free-standing GaN substrates are used for blue and green laser diodes, then manufacturing precision and device performance are improved, but substrate cost increases significantly
Solution Approach 1:
The patent extracts the laser diode active region from the expensive free-standing GaN substrate by using a sacrificial layer that can be selectively removed. This allows the active region to be transferred to a cheaper carrier substrate, maintaining device performance while reducing substrate cost.
Solution Approach 2:
The patent introduces a sacrificial layer as an intermediary between the epitaxial active region and the final carrier substrate. This sacrificial layer enables temporary support during fabrication and transfer, then is selectively removed to release the active region for mounting on the cheaper carrier.
2Use of energy by moving object
If diode-pumped solid state lasers are used for visible wavelengths, then wall plug efficiency is improved to 5-10%, but system cost and temperature sensitivity increase
Solution Approach 1:
The patent extracts the frequency conversion crystal from the complex diode-pumped solid state laser system, using direct blue laser diodes instead. This eliminates the need for 1064nm laser generation and second harmonic conversion, reducing system cost and temperature sensitivity while maintaining efficiency.
Solution Approach 2:
Instead of using infrared laser diodes with frequency conversion (the conventional approach), the patent inverts the approach by using direct blue laser diodes that emit at the desired visible wavelength, eliminating the conversion step and its associated problems.
3Quantity of substance
If epitaxial material pitch is expanded for carrier wafer transfer, then manufacturing cost is reduced, but device density decreases
Solution Approach 1:
The patent segments the fabrication process into two stages: first fabricating multiple active regions on a large-area epitaxial wafer, then transferring them to a carrier substrate. This allows optimized pitch for fabrication while achieving high device density on the final product through the transfer process.
Solution Approach 2:
The patent uses the carrier substrate as a separate dimension for final device arrangement. Devices are fabricated at one pitch on the epitaxial wafer, then transferred and arranged at a different pitch on the carrier, allowing optimization of each stage independently.
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 reduces the cost of blue-light emitting laser diodes to a competitive level with LEDs, enabling widespread penetration into general lighting markets and improving modularity and efficiency by using conventional processing technology.
Implementation Method 1
forming epitaxial material overlying the surface region
Data Source
AI summary
A multi-emitter laser diode device includes a carrier chip singulated from a carrier wafer. The carrier chip has a length and a width, and the width defines a first pitch. The device also includes a plurality of epitaxial mesa dice regions transferred to the carrier chip from a substrate and attached to the carrier chip at a bond region. Each of the epitaxial mesa dice regions is arranged on the carrier chip in a substantially parallel configuration and positioned at a second pitch defining the distance between adjacent epitaxial mesa dice regions. Each of the plurality of epitaxial mesa dice regions includes epitaxial material, which includes an n-type cladding region, an active region having at least one active layer region, and a p-type cladding region. The device also includes one or more laser diode stripe regions, each of which has a pair of facets forming a cavity region.