GaN Contact Region Laser Scribing for Low Resistance
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Solution Overview
Problem
Existing optical devices, particularly lasers and light emitting diodes, face inefficiencies, high costs, and difficulties in modulating at high speeds due to energy storage properties and sensitivity to temperature, especially in producing blue and green wavelengths.
Innovation Solution
A method and device using a laser scribing process to ablate a portion of the contact region on nonpolar gallium-containing substrates like GaN, forming a gallium rich region and improving device performance by reducing contact resistance and voltage drop, achieved through localized high temperature annealing and intermixing between the contact metal and substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional contact regions are used in optical devices, then manufacturing is simpler, but contact resistance is higher and voltage drop increases
Solution Approach 1:
The laser treatment is performed on the contact region before metallization deposition. This preliminary action modifies the substrate surface properties, creating a gallium-rich region that improves subsequent metal contact formation and reduces contact resistance without adding complex post-processing steps
Solution Approach 2:
The laser treatment is applied locally to specific contact regions rather than uniformly across the entire substrate. This creates localized gallium-rich zones exactly where metal contacts will be deposited, improving contact properties only where needed while leaving the rest of the device structure unchanged
2Use of energy by moving object
If lamp pumped solid state lasers are used, then red and infrared wavelengths are achieved, but efficiency and cost are poor for blue and green wavelengths
Solution Approach 1:
The patent replaces complex lamp pumping mechanisms with direct electrical injection into semiconductor structures. By treating the contact regions of GaN-based LEDs and lasers with laser processing, the device can be efficiently driven electrically rather than optically, improving energy conversion efficiency and reducing system complexity
Solution Approach 2:
The laser treatment changes the physical and chemical parameters of the contact region, including creating gallium-rich zones and modifying surface morphology. These parameter changes enable better electrical contact and carrier injection, directly improving the energy efficiency of blue and green wavelength devices
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
The approach enables cost-effective manufacturing of optical devices with improved contact resistance and reduced voltage drop, enhancing the performance and efficiency of lasers and light emitting diodes, particularly in emitting wavelengths of 395, 405, 450, 485, and 520 nanometers.
Implementation Method 1
uses a laser scribing process to ablate a portion of a contact region for improved device performance
Implementation Method 2
subjecting the contact region in a portion of the substrate to a laser scribing process to form a scribe region causing a gallium rich region
Implementation Method 3
improved contact resistance and reduced voltage drop, achieved through localized high temperature annealing and intermixing between the contact metal and substrate
Data Source
AI summary
A method for forming optical devices includes providing a gallium nitride substrate having a crystalline surface region and a backside region. The backside is subjected to a laser scribing process to form scribe regions. Metal contacts overly the scribe regions.