Germanium Epitaxial Layer Defect Reduction via Segmented Deposition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional avalanche photodiodes with germanium epitaxial layers have high defect density, leading to increased dark current and reduced detection accuracy due to the required thickness of the germanium epitaxial layer.
Innovation Solution
A method involving alternating deposition and annealing processes to form a germanium epitaxial layer, where a first germanium epitaxial film is deposited and annealed, followed by a second germanium epitaxial film, resulting in a thicker layer with reduced defect density and dark current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single deposition process and single annealing process are used to form the germanium epitaxial layer, then the manufacturing process is simple, but the defect density in the germanium epitaxial layer is high
Solution Approach 1:
The single deposition and annealing process is segmented into multiple alternating cycles. The patent performs first deposition, first annealing, second deposition, and second annealing processes alternately at least two times. This segmentation allows each individual deposition and annealing step to be optimized, reducing defect accumulation while maintaining overall process manageability.
Solution Approach 2:
The patent employs periodic alternating deposition and annealing processes. By cycling between deposition (adding germanium material) and annealing (heating to reduce defects) multiple times, the system achieves progressive defect reduction while building the required layer thickness, transforming a continuous problematic process into discrete controllable cycles.
2Reliability
If the germanium epitaxial layer is made thicker to improve light absorption, then the detection capability is enhanced, but the defect density increases leading to higher dark current
Solution Approach 1:
The thick germanium epitaxial layer is constructed through multiple thin film depositions rather than a single thick layer. Each thin film undergoes individual annealing treatment, allowing defects to be managed at each stage. This segmented construction achieves the required thickness for light absorption while minimizing cumulative defect density that would generate dark current.
Solution Approach 2:
The alternating deposition and annealing processes continue cyclically to progressively build the thick germanium layer with continuously improving quality. Each cycle adds material and then heals defects, maintaining continuous progress toward the target thickness while continuously reducing defect density, ensuring both detection capability and low dark current.
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 method effectively lowers the dark current and enhances the detection accuracy of avalanche photodiodes by reducing defect density in the germanium epitaxial layer through multiple deposition and annealing processes.
Implementation Method 1
a first deposition process is performed to deposit a first germanium epitaxial film on the substrate
Implementation Method 2
a first annealing process is performed on the first germanium epitaxial film
Data Source
AI summary
A method for manufacturing a germanium (Ge) epitaxial layer is provided. First, a substrate is provided. Then, a first deposition process is performed to deposit a first Ge epitaxial film on the substrate. Next, a first annealing process is performed on the first Ge epitaxial film. Following that, a second deposition process is performed to directly deposit a second Ge epitaxial film on the first Ge epitaxial film. Thereafter, a second annealing process is performed on the second Ge epitaxial film, wherein the Ge epitaxial layer includes the first Ge epitaxial film and the second Ge epitaxial film, and a thickness of the Ge epitaxial layer is greater than 0.5 microns.