LED Contact and Mirror Layer Stack for Uniform Forward Voltage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for producing optoelectronic components, such as LEDs, face challenges in achieving a homogeneous light pattern and good forward voltage due to uncontrollable contact resistance and reflectivity, which affect the brightness and efficiency of the components.
Innovation Solution
A method involving the application of a thin contact layer (≤10 nm) directly onto the semiconductor layer sequence, followed by a mirror layer and a barrier layer, decouples contact formation from diffusion processes, allowing for controlled contact resistance and reflectivity optimization, and using materials like zinc or zinc oxide to prevent silver diffusion and enhance layer growth and crystal orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a heat-treatment step is applied to modify the structure of the mirror material, then the contact resistance and reflectivity are modified, but the control over these parameters becomes limited and uncontrollable
Solution Approach 1:
The patent segments the previously combined heat-treatment process into separate sequential steps: first depositing the mirror layer, then applying the contact layer, and finally adding the barrier layer. This segmentation allows independent optimization of each layer's properties without the uncontrollable diffusion processes that occurred during heat-treatment, thereby improving manufacturing precision while maintaining manageable process complexity
Solution Approach 2:
The contact layer is applied preliminarily before the barrier layer, with controlled thickness (at most 10 nm), to establish proper electrical contact before preventing silver diffusion. This preliminary action ensures that contact resistance is optimized before the barrier layer is added, allowing precise control over both contact resistance and reflectivity independently
2Illumination intensity
If the mirror layer structure is modified through deposition and heat-treatment, then reflectivity changes, but the brightness and efficiency of the LED cannot be optimized to the desired extent
Solution Approach 1:
The patent applies local quality by creating distinct layers with specific localized functions: the mirror layer provides high reflectivity, the contact layer (at most 10 nm thick) provides optimized electrical contact, and the barrier layer prevents silver diffusion. This localized optimization of each layer's properties enables independent tuning of reflectivity and contact resistance to maximize brightness and efficiency
Solution Approach 2:
The patent uses composite material structures combining different materials in specific layers: silver or aluminum for the mirror layer, zinc or zinc oxide for the contact layer, and titanium tungsten or titanium nitride for the barrier layer. This composite approach allows each material to contribute its optimal properties, achieving superior brightness and efficiency through controlled reflectivity and contact resistance
3Reliability
If a thicker contact layer is used to improve contact resistance, then contact properties improve, but diffusion of mirror layer material increases and reflectivity deteriorates
Solution Approach 1:
The patent precisely controls the thickness parameter of the contact layer to be at most 10 nm, which is optimized to provide sufficient electrical contact while preventing excessive diffusion that would degrade the mirror layer's reflectivity. This parameter optimization allows simultaneous achievement of low contact resistance and high brightness
Solution Approach 2:
The contact layer acts as an intermediary between the mirror layer and the semiconductor layer sequence, providing a controlled interface that ensures good electrical contact without allowing uncontrolled diffusion. The barrier layer then serves as a second intermediary to prevent any remaining silver diffusion, thus protecting the mirror layer's reflectivity while maintaining reliable contact
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 method results in a stable process with independent optimization of p-contact resistance, mirror reflectivity, and barrier properties, leading to increased brightness and a homogeneous distribution of forward voltage in optoelectronic components.
Implementation Method 1
applying a contact layer, which prevents or reduces diffusion of the material of a mirror layer, directly onto the semiconductor layer sequence
Implementation Method 2
silver on the p-side of the epitaxial layer, which acts as a compact and as a mirror
Implementation Method 3
The semiconductor layer sequence is adapted for radiation emission. During operation of the component, electromagnetic radiation is generated in the active layer
Data Source
AI summary
A method for producing an optoelectronic component by providing a semiconductor layer sequence on a substrate where the semiconductor layer sequence is configured to emit radiation. The method may further include applying a contact layer to the semiconductor layer sequence where the contact layer has a layer thickness of at most 10 nm. The method may further include applying a reflective layer to the contact layer and applying a barrier layer directly to the reflective layer.