Nitride Semiconductor Chip on Silicon Substrate with AlN Buffer
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Solution Overview
Problem
The production of nitride compound semiconductor LEDs on silicon substrates faces challenges due to lattice mismatch, leading to strain and reduced crystal quality, and existing substrate materials like sapphire are expensive.
Innovation Solution
An optoelectronic semiconductor chip with a nitride compound semiconductor layer stack grown on a silicon carrier substrate, featuring a recess for electrical connection, nanostructures for defect reduction, and an InGaN conversion element integrated into the nanostructures to convert radiation, allowing for inexpensive production and reduced strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sapphire or silicon carbide substrate is used for epitaxial growth, then crystal quality and lattice matching are improved, but production cost increases significantly
Solution Approach 1:
A multi-layer buffer structure consisting of AlN and AlGaN layers is introduced between the silicon substrate and the nitride compound semiconductor layer sequence. This buffer structure acts as an intermediary that gradually transitions the lattice parameters, reducing strain and preventing dislocation propagation while enabling the use of inexpensive silicon substrates for high-quality LED growth
Solution Approach 2:
The buffer structure employs composite materials with varying aluminum compositions (AlN and AlGaN layers) to create a gradient that matches the lattice parameters between silicon substrate and GaN-based active layers, achieving both cost reduction and maintained crystal quality
2Ease of manufacture
If silicon substrate is used for growth, then production cost decreases, but strain and dislocation increase due to lattice mismatch
Solution Approach 1:
The AlN/AlGaN buffer structure serves as a mediator that compensates for the lattice mismatch between silicon and nitride compounds, enabling inexpensive silicon substrates to support high-quality semiconductor growth by progressively adapting the crystal structure
Solution Approach 2:
The buffer layers utilize varying aluminum composition parameters (from AlN to AlGaN with different Ga contents) to create a gradual lattice parameter transition, reducing strain accumulation and dislocation formation while maintaining structural integrity
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 solution enables the production of inexpensive semiconductor chips with reduced strain and high crystal quality, achieving efficient radiation emission and conversion, including white light emission without additional phosphors, with improved thermal stability and light outcoupling efficiency.
Implementation Method 1
a conversion element is arranged on the front which converts at least some of the radiation emitted by the active layer into radiation of another wavelength
Implementation Method 2
epitaxially growing the semiconductor layer stack on the surface
Data Source
AI summary
An optoelectronic semiconductor chip includes a semiconductor layer stack including a nitride compound semiconductor material on a carrier substrate, wherein the semiconductor layer stack includes an active layer that emits an electromagnetic radiation, the semiconductor layer stack being arranged between a layer of a first conductivity and a layer of a second conductivity, the layer of the first conductivity is adjacent a front of the semiconductor layer stack, the layer of the first conductivity electrically connects to a first electrical connection layer covering at least a portion of a back of the semiconductor layer stack, and the layer of the second conductivity type electrically connects to a second electrical connection layer arranged at the back.