APD Photodetector Layout for Accurate On-Substrate Temperature Compensation
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Solution Overview
Problem
Existing light detection devices face challenges in achieving accurate temperature compensation for avalanche photodiodes (APDs) while maintaining low manufacturing costs, particularly in high-temperature environments, where carrier generation due to heat affects detection accuracy.
Innovation Solution
A light detection device is designed with an avalanche photodiode (APD) and a temperature compensation diode formed on the same semiconductor substrate, separated by a peripheral carrier absorbing portion, which suppresses carriers generated by heat or light emission, ensuring accurate temperature compensation and improved detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If APD and temperature compensation diode are formed on the same semiconductor substrate, then manufacturing cost is reduced, but detection accuracy deteriorates due to carrier interference
Solution Approach 1:
The semiconductor substrate is segmented into distinct functional regions: an APD formation region, a temperature compensation diode formation region, and a peripheral carrier absorbing portion. This spatial segmentation prevents carrier interference while maintaining cost benefits of single-substrate fabrication.
Solution Approach 2:
A peripheral carrier absorbing portion is introduced as an intermediary element between the APD and temperature compensation diode. This carrier absorbing structure captures excess carriers generated in the temperature compensation diode, preventing them from interfering with APD detection while allowing both devices to coexist on the same substrate.
2Measurement precision
If APD and temperature compensation diode are formed on different semiconductor substrates, then detection accuracy is improved by eliminating carrier interference, but manufacturing cost increases
Solution Approach 1:
The patent merges the APD and temperature compensation diode onto a single semiconductor substrate, reducing manufacturing costs. However, this merging introduces carrier interference, which is resolved by adding a peripheral carrier absorbing portion to enable accurate operation despite the combined substrate configuration.
3Reliability
If temperature compensation diode emits light in high temperature environment, then temperature compensation function is achieved, but carrier generation increases causing detection noise
Solution Approach 1:
The light emitted by the temperature compensation diode, which normally generates harmful carriers, is converted into a beneficial effect. The peripheral carrier absorbing portion captures these light-generated carriers, preventing noise while allowing the temperature compensation diode to emit light for accurate temperature compensation in high-temperature environments.
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 device achieves improved detection accuracy by effectively absorbing carriers generated in high-temperature environments, allowing for precise temperature compensation of the APD multiplication factor while reducing manufacturing costs.
Implementation Method 1
In such a high temperature environment, carriers due to heat are generated in the semiconductor substrate forming the APD
Implementation Method 2
The semiconductor substrate includes a peripheral carrier absorbing portion configured to absorb carriers located at the periphery
Implementation Method 3
When a breakdown voltage is applied to the temperature compensation diode, the temperature compensation diode may emit light
Implementation Method 4
When the temperature compensation diode emits light, carriers are generated in the semiconductor substrate due to the light emitted from the temperature compensation diode
Data Source
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AI summary
A light detection device 1 includes a semiconductor substrate 10. The semiconductor substrate 10 forms an APD 11 and a temperature compensation diode 12 so as to be spaced apart from each other when viewed from a direction perpendicular to a main surface 10a. The semiconductor substrate 10 includes a peripheral carrier absorbing portion 13 surrounding the APD 11 when viewed from the direction perpendicular to the first main surface 10a and configured to absorb carriers located at the periphery. A part of the peripheral carrier absorbing portion 13 is located between the APD 11 and the temperature compensation diode 12 when viewed from the direction perpendicular to the main surface 10a.