Transparent Buried Contacts for Higher-Reflectivity SSRT Emitters
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional solid-state radiation transducer devices with buried-contact configurations face issues with poor current spreading and interference with light emissions due to low reflectivity at the interfaces between buried-contact elements and semiconductor materials, leading to reduced lumen output and efficiency, especially when color-converting materials are present.
Innovation Solution
The use of buried-contact elements that are at least partially transparent, allowing for improved electrical connections and reduced interference with light emissions by using conductive and transparent materials like indium tin oxide, doped zinc oxide, or carbon allotropes, which facilitate better reflectivity and current spreading without forming low-reflectivity alloys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional metal contacts are used for buried contacts, then electrical connection is achieved, but light reflectivity is reduced due to formation of low-reflectivity alloys
Solution Approach 1:
A transparent conductive oxide layer (indium tin oxide or doped zinc oxide) is introduced as an intermediary material between the metal contact and the semiconductor layer. This intermediate layer allows the metal to provide electrical connection while the transparent oxide maintains high light reflectivity by preventing direct contact between metal and semiconductor that would form low-reflectivity alloys.
Solution Approach 2:
The buried contact structure uses a composite material system combining metal (for electrical conductivity) with transparent conductive oxide (for optical transparency and reflectivity). This composite approach allows simultaneous achievement of reliable electrical connection and high light reflectivity, resolving the contradiction between electrical performance and optical performance.
2Reliability
If the second contact extends across a significant portion of the N-type layer to facilitate current spreading, then current spreading is improved, but interference with light emissions increases
Solution Approach 1:
The contact structure is designed with spatially varying properties: the transparent conductive oxide layer is present only in specific regions where electrical connection is needed, while leaving other regions transparent for light emission. This local differentiation allows current spreading to be enhanced in contact regions without interfering with light emissions in non-contact regions.
Solution Approach 2:
The transparent conductive oxide material is selected to be transparent to the wavelength of emitted light, effectively making it 'invisible' to the emitted radiation. This optical transparency allows the contact to perform its electrical function without visually or optically interfering with the light emissions, resolving the contradiction between current spreading and light emission interference.
3Illumination intensity
If transparent conductive oxide materials are used for buried contacts, then light reflectivity is maintained, but manufacturing complexity increases
Solution Approach 1:
The manufacturing process utilizes parameter changes in the form of sputtering power adjustments to deposit transparent conductive oxide materials. By controlling sputtering parameters (power, gas flow, temperature), the process achieves the desired film properties (thickness, conductivity, transparency) in a controlled manner, making the manufacturing process manageable despite the added material layer.
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 configuration enhances lumen output, efficiency, and output uniformity by allowing a significant percentage of light to be reflected back towards the emitting side, reducing dark spots and improving performance in display and projection applications.
Implementation Method 1
Incorporation of at least partially transparent buried-contact elements, formed using materials like indium tin oxide or doped zinc oxide, to facilitate electrical connection
Implementation Method 2
allowing light to pass through and be reflected back efficiently
Implementation Method 3
at least partially transparent buried-contact elements, formed using materials like indium tin oxide or doped zinc oxide
Implementation Method 4
facilitate electrical connection without forming low-reflectivity alloys
Data Source
AI summary
Solid-state radiation transducer (SSRT) devices having buried contacts that are at least partially transparent and associated systems and methods are disclosed herein. An SSRT device configured in accordance with a particular embodiment can include a radiation transducer including a first semiconductor material, a second semiconductor material, and an active region between the first semiconductor material and the second semiconductor material. The SSRT device can further include first and second contacts electrically coupled to the first and second semiconductor materials, respectively. The second contact can include a plurality of buried-contact elements electrically coupled to the second semiconductor material. Individual buried-contact elements can have a transparent portion directly adjacent to the second semiconductor material. The second contact can further include a base portion extending between the buried-contact elements, such as a base portion that is least partially planar and reflective.