Strain-Tunable Ge P-I-N Diodes for Spectral Control
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Solution Overview
Problem
Current semiconductor technologies using germanium (Ge) lack tunability and efficient radiation emission across a wide spectral range, particularly in the 1.5 to 2.5 μm range, which is crucial for applications like biological sensing, spectroscopy, and free-space optical communications.
Innovation Solution
A tunable p-i-n diode with a Ge heterojunction structure affixed to a mechanically stretchable substrate, where biaxial tensile strain is induced using a stretching actuator, transforming Ge into a direct-bandgap semiconductor material capable of emitting radiation via electroluminescence, with adjustable wavelengths by varying the strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If germanium is used as a semiconductor material for optoelectronic applications, then strong interband absorption at near-infrared wavelengths is achieved, but the material lacks tunability and efficient radiation emission across a wide spectral range
Solution Approach 1:
The patent applies parameter changes by inducing biaxial tensile strain in the germanium layer through a stretching actuator that expands the substrate. This strain modifies the band structure of germanium, transforming it from indirect-bandgap to direct-bandgap, thereby enabling efficient radiation emission and achieving spectral tunability across 1.5 to 2.5 μm wavelengths.
Solution Approach 2:
The patent implements dynamics by using a mechanically expandable substrate with a stretching actuator that can dynamically adjust the strain level in the germanium layer. This allows real-time tuning of the emission wavelength and spectral characteristics, transforming the static germanium material into a dynamically adjustable light source.
2Reliability
If germanium is transformed into a direct-bandgap semiconductor through biaxial tensile strain, then efficient radiation emission is achieved, but device complexity increases due to the need for stretchable substrates and actuators
Solution Approach 1:
The patent employs flexible shells and thin films by using a mechanically expandable substrate that can be stretched without breaking. This flexible substrate supports the germanium heterojunction structure and enables the application of biaxial tensile strain through controlled expansion, simplifying the overall device architecture while achieving the desired strain effect.
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
Enables efficient radiation emission across a technologically significant spectral range, supporting population inversion and optical gain, enhancing the diodes' applicability in various fields.
Implementation Method 1
a stretching actuator configured to stretch the mechanically stretchable substrate and the affixed p-i-n heterojunction structure to induce a biaxial tensile strain in the Ge. The induced biaxial tensile strain can be sufficiently large to transform the Ge into a direct-bandgap semiconductor material.
Implementation Method 2
applying a voltage across the tensilely strained p-i-n heterojunction structure, wherein radiation is emitted via electroluminescence
Data Source
AI summary
Tunable p-i-n diodes comprising Ge heterojunction structures are provided. Also provided are methods for making and using the tunable p-i-n diodes. Tunability is provided by adjusting the tensile strain in the p-i-n heterojunction structure, which enables the diodes to emit radiation over a range of wavelengths.