Optoelectronic Semiconductor Chip Nanostructures
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Solution Overview
Problem
Conventional semiconductor chips face issues with lattice dislocations and point defects due to substrate differences, leading to reduced quantum efficiency and leakage current, and existing surface treatment methods limit the shape and size of surface structures for optimal radiation emission.
Innovation Solution
The use of nanostructures with substructures in the semiconductor layer stack or on the radiation exit/entrance face, produced by methods like metal organic vapor phase epitaxy, molecular beam epitaxy, or liquid phase epitaxy, which increase the surface area and reduce dislocation density, enabling improved quantum efficiency and angle-independent radiation emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional substrate materials are used for growing semiconductor layers, then the manufacturing process is simple, but lattice dislocations and point defects arise due to differences in coefficient of expansion and lattice parameters, reducing quantum efficiency
Solution Approach 1:
The substrate system is segmented into multiple layers: a first substrate for growing the semiconductor layer stack, and a second substrate for receiving the completed stack. This segmentation allows each substrate to be optimized for its specific function, reducing defects while maintaining manufacturing simplicity.
Solution Approach 2:
A buffer layer is introduced as an intermediary between the first substrate and the semiconductor layer stack. This buffer layer mediates the lattice mismatch and thermal expansion differences, preventing dislocations from propagating into the active semiconductor layers while allowing the use of conventional substrate materials.
2Illumination intensity
If wet chemical etching is used to treat the semiconductor chip surface, then light outcoupling is improved, but the shape and size of surface structures are limited by selective chemical reaction
Solution Approach 1:
The chemical etching process is replaced with a physical vapor deposition process. Nanostructures are deposited using physical vapor deposition methods, allowing precise control of shape and size through deposition parameters rather than chemical selectivity, while achieving superior light outcoupling efficiency.
Solution Approach 2:
The manufacturing approach changes from chemical removal (etching) to physical deposition. By controlling deposition parameters such as temperature, pressure, and material flux, the shape and size of nanostructures can be precisely tuned to optimize both light outcoupling and emission characteristics.
3Illumination intensity
If the incident radiation angle is kept smaller than the critical angle for total reflection, then light coupling is improved, but radiation emission is angle-dependent and not maximized
Solution Approach 1:
The surface is modified by adding vertical nanostructures that extend into the third dimension. These nanostructures create multiple emission interfaces at different angles, enabling light to escape in various directions rather than being constrained to a single critical angle, thus achieving angle-independent radiation emission.
Solution Approach 2:
The planar surface is replaced with curved or rounded nanostructure surfaces. The curved surfaces of the nanostructures refract and reflect light at multiple angles, distributing radiation emission across a wide angular range and eliminating the sharp cutoff at the critical angle for total reflection.
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 nanostructures with substructures enhance the internal and external quantum efficiency of semiconductor chips by reducing non-emitting or non-receiving recombination centers and allowing the use of substrates with different expansion coefficients, resulting in improved radiation emission and detection efficiency.
Implementation Method 1
the nanostructures are produced by metal organic vapor phase epitaxy, molecular beam epitaxy or liquid phase epitaxy
Data Source
AI summary
An optoelectronic semiconductor chip includes a semiconductor layer stack and a radiation exit face or radiation entrance face, wherein the semiconductor layer stack includes an active layer that generates or receives electromagnetic radiation, and a plurality of nanostructures arranged in the semiconductor layer stack and/or on the radiation exit or entrance face, at least some of the nanostructures including at least one substructure.