Germanium Avalanche Photodiode Lateral Electrode Voltage Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Avalanche photodiodes require high bias voltages for operation in optical communication systems, leading to high power consumption and fabrication challenges, particularly in scaling for optical electronics within optical circuits.
Innovation Solution
A germanium-based avalanche photodiode device with a silicon substrate, doped regions, and a germanium waveguide structure that reduces operating voltage and simplifies manufacturing by using lateral electrodes and epitaxial growth methods to form doped regions and waveguides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional avalanche photodiodes are used, then avalanche multiplication gain is achieved, but high bias voltage (>25V) is required leading to high power consumption
Solution Approach 1:
The device is divided into distinct functional regions: a silicon multiplication region for avalanche gain and a germanium absorption region for light detection. This segmentation allows each region to be optimized independently, enabling the multiplication region to operate at lower voltages while maintaining gain functionality.
Solution Approach 2:
The patent employs a composite structure combining silicon and germanium materials. The silicon multiplication region provides avalanche multiplication capability, while the germanium absorption region offers superior light absorption. This composite material approach enables reduced bias voltage operation compared to conventional single-material APDs.
2Reliability
If avalanche photodiodes are deployed in optical communication systems, then sensitive light detection is achieved, but fabrication difficulties arise when scaling for optical electronics
Solution Approach 1:
The patent merges the multiplication function and absorption function into a single integrated device structure. The silicon multiplication region and germanium absorption region are grown together in a unified epitaxial process, eliminating the need for separate device fabrication steps and reducing overall manufacturing complexity.
Solution Approach 2:
The patent transitions from planar device structures to a vertical layered architecture. Light propagates through the device in the vertical dimension, passing through the germanium absorption region and generating carriers in the silicon multiplication region. This vertical stacking enables compact integration and simplifies fabrication processes.
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 reduces the operating voltage to around 10V, enhancing power efficiency and ease of manufacturing, making it suitable for optical communication systems.
Implementation Method 1
avalanche photodiodes can be thought of as providing gain through avalanche multiplication. Avalanche breakdown is a phenomena in which, through the application of an electric field, charge carriers cause the production of other charge carriers within a multiplication region of a device
Implementation Method 2
Avalanche breakdown is a phenomena in which, through the application of an electric field, charge carriers cause the production of other charge carriers within a multiplication region of a device
Data Source
AI summary
A germanium based avalanche photo-diode device and method of manufacture thereof. The device including: a silicon substrate; a lower doped silicon region, positioned above the substrate; a silicon multiplication region, positioned above the lower doped silicon region; an intermediate doped silicon region, positioned above the silicon multiplication region; an un-doped germanium absorption region, position above the intermediate doped silicon region; an upper doped germanium region, positioned above the un-doped germanium absorption region; and an input silicon waveguide; wherein: the un-doped germanium absorption region and the upper doped germanium region form a germanium waveguide which is coupled to the input waveguide, and the device also includes a first electrode and a second electrode, and the first electrode extends laterally to contact the lower doped silicon region and the second electrode extends laterally to contact the upper doped germanium region.