Avalanche Photodiode Carbon Activation via Inert Gas Annealing
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Solution Overview
Problem
The activation rate of carbon in the p-type field relaxation layer of avalanche photodiodes is hindered by hydrogen introduction during the growth of the light absorbing layer, leading to heat damage and reduced reliability, as longer annealing times exacerbate hydrogen concentration and crystalline deterioration.
Innovation Solution
A manufacturing method involving a temperature-rise process from the growth temperature of the cap layer to the light absorbing layer in an inactive gas atmosphere without introducing group V raw materials, such as AsH3, to prevent hydrogen incorporation and maintain the carbon activation rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If annealing time is extended to improve carbon activation, then carbon activation rate improves up to a point, but heat damage to the field relaxation layer increases
Solution Approach 1:
The patent performs the carbon activation annealing as a preliminary step before introducing group V raw materials. By completing the heat treatment necessary for carbon activation in N2 atmosphere first, the process achieves adequate carbon activation with limited exposure time, thereby minimizing heat damage to the AlInAs field relaxation layer while still achieving the required activation level.
Solution Approach 2:
The patent changes the atmospheric composition parameter from N2 to group V-containing atmosphere after carbon activation is initiated. This parameter change allows the process to achieve carbon activation with controlled, limited thermal exposure, preventing excessive heat damage while maintaining effective dopant activation.
2Ease of manufacture
If group V raw material such as AsH3 is introduced during light absorbing layer growth, then the light absorbing layer can be formed, but hydrogen is taken into the field relaxation layer reducing carbon activation rate
Solution Approach 1:
The patent segments the manufacturing process into distinct phases: carbon activation annealing in N2 atmosphere is performed separately before the growth of the light absorbing layer with group V raw materials. This temporal and functional segmentation ensures that hydrogen from AsH3 decomposition does not contaminate the AlInAs field relaxation layer during the critical carbon activation period, maintaining high carbon activation rates while still enabling subsequent light absorbing layer formation.
Solution Approach 2:
The carbon activation annealing is performed as a preliminary action before introducing group V raw materials for light absorbing layer growth. This preliminary carbon activation in N2 atmosphere establishes the required dopant activation level before hydrogen contamination becomes a risk, ensuring that the field relaxation layer maintains its electrical properties even after subsequent processing steps.
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
This approach enhances the carbon activation rate in the p-type field relaxation layer by minimizing hydrogen incorporation and heat damage, thereby improving the reliability and performance of the avalanche photodiode.
Implementation Method 1
execution of annealing can be considered between the growth of the field relaxation layer and the growth of the light absorbing layer
Implementation Method 2
a rise of hydrogen concentration is observed, and this is considered to be caused by a group V raw material such as AsH3 introduced into a device during the growth of the light absorbing layer
Data Source
AI summary
A manufacturing method of an avalanche photodiode includes: forming a p-type field relaxation layer on a substrate; forming a cap layer on the p-type field relaxation layer; and forming a light absorbing layer on the cap layer, wherein a carbon is doped in the p-type field relaxation layer as a p-type dopant, the p-type field relaxation layer contains Al in a crystal composition, and a temperature-rise process from a growth temperature of the cap layer to a growth temperature of the light absorbing layer is performed in an inactive gas atmosphere without introducing a group V raw material.