Chirp Layer Superlattice for Hot Electron Damage Mitigation
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Solution Overview
Problem
Semiconductor devices face degradation due to hot electrons overshooting from wide bandgap to narrow bandgap regions, causing energy release that can damage the crystal lattice and reduce device efficiency and lifetime.
Innovation Solution
Incorporating a chirp layer with alternating layers of wide and narrow bandgap materials in a superlattice structure that gradually releases electron energy in small steps, mitigating structural changes and defect formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If electrons travel from wide bandgap region to narrow bandgap region, then carrier transport is achieved, but hot electrons cause structural damage and device degradation
Solution Approach 1:
The interface region is segmented into multiple thin alternating layers of wide and narrow bandgap materials forming a superlattice structure. This segmentation creates multiple intermediate energy steps that gradually reduce electron energy, preventing hot electron damage while maintaining carrier transport efficiency.
Solution Approach 2:
The superlattice structure acts as an intermediary layer between the wide bandgap and narrow bandgap regions. It mediates the energy transition of electrons by providing multiple intermediate energy states, allowing gradual energy release without causing structural damage to the crystal lattice.
2Device complexity
If conventional interface structure is used, then device complexity is low, but hot electrons cause permanent damage and efficiency degradation
Solution Approach 1:
The interface structure uses composite materials consisting of alternating wide and narrow bandgap semiconductor layers. This composite superlattice structure provides tailored energy band alignment that gradually reduces electron energy, eliminating hot electron damage while maintaining reasonable structural complexity.
3Reliability
If alternating layers of wide and narrow bandgap materials are used, then electron energy is released in small steps reducing damage, but manufacturing complexity increases
Solution Approach 1:
The interface is divided into multiple thin alternating layers that can be deposited using standard molecular beam epitaxy techniques. Each layer is thin enough to be grown sequentially in a single deposition process, making the segmented structure manufacturable with existing technology.
Solution Approach 2:
The layer thicknesses and material compositions are optimized to achieve the desired energy band structure. By carefully controlling deposition parameters such as layer thickness and growth rate, the superlattice structure can be manufactured with precise control over its electronic properties.
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
Improves the lifetime of semiconductor devices by reducing degradation and maintaining efficiency through controlled electron energy release, enhancing performance in UV-C LEDs, UV-A LEDs, bipolar junction transistors, power transistors, and semiconductor lasers.
Implementation Method 1
a chirp layer with alternating layers of wide and narrow bandgap materials in a superlattice structure that gradually releases electron energy in small steps
Data Source
AI summary
A semiconductor structure can comprise a plurality of first semiconductor layers comprising wide bandgap semiconductor layers, a narrow bandgap semiconductor layer, and a chirp layer between the plurality of first semiconductor layers and the narrow bandgap semiconductor layer. The plurality of first semiconductor layers can comprise a first short-period superlattice (SPSL). The chirp layer can comprise alternating layers of GaN layers and AlN layers. An average composition of Al/(Al+Ga) of the chirp layer changes throughout the chirp layer.