Three-Terminal Monolithic Photodetector for Ultralow Voltage Operation
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Solution Overview
Problem
Conventional monolithic avalanche photodetectors require high bias voltages for operation, making them incompatible with low-voltage electronics platforms such as servers and mobile devices.
Innovation Solution
A three-terminal photodetector architecture is developed, where two p-i-n semiconductor junctions are monolithically integrated with shared terminals, allowing for avalanche multiplication of photogenerated carriers at ultralow voltages below 10V, specifically between 4.5 and 5.5V, by separating voltage drops across the terminals, enabling operation at lower voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional monolithic APD diode structure is used, then high sensitivity is achieved through carrier multiplication, but high bias voltage (around 20V) is required which makes it incompatible with low-voltage electronics platforms
Solution Approach 1:
The patent divides the conventional two-terminal APD structure into three separate terminals: an anode terminal, a cathode terminal, and a multiplication terminal. This segmentation allows the voltage to be distributed across different regions - the absorption region between anode and multiplication terminal, and the multiplication region between multiplication terminal and cathode terminal. By applying voltage across the anode and cathode terminals, the patent achieves carrier multiplication at the multiplication terminal while operating at lower overall voltages (below 10V) compared to conventional designs requiring around 20V.
2Reliability
If high bias voltage is applied to achieve carrier multiplication in conventional APD, then sensitivity is improved, but compatibility with low-voltage electronics platforms (servers, mobile devices) is lost
Solution Approach 1:
The three-terminal configuration enables the photodetector to be integrated into low-voltage electronics platforms by segmenting the voltage requirements. The absorption region and multiplication region are electrically separated, allowing the device to operate within the voltage constraints of modern electronics (below 10V, specifically 4.5-5.5V) while still achieving the necessary carrier multiplication for high sensitivity applications.
Solution Approach 2:
The patent changes the electrical parameters of the APD by introducing a third terminal that controls the multiplication process independently. By adjusting the voltage distribution across the three terminals, the device achieves carrier multiplication at lower operating voltages, making it adaptable to various electronics platforms including servers and mobile devices that operate at low voltages.
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 three-terminal photodetector achieves carrier multiplication at significantly lower voltages than conventional designs, enhancing compatibility with a broader range of electronic devices and maintaining high sensitivity and bandwidth capabilities.
Implementation Method 1
A multiplication region of the first p-i-n structure is biased to multiply charge carriers photogenerated within an absorption region of the second p-i-n structure
Data Source
AI summary
Photodetectors operable to achieve multiplication of photogenerated carriers at ultralow voltages. Embodiments include a first p-i-n semiconductor junction combined with a second p-i-n semiconductor junction to form a monolithic photodetector having at least three terminals. The two p-i-n structures may share either the p-type region or the n-type region as a first terminal. Regions of the two p-i-n structures doped complementary to that of the shared terminal form second and third terminals so that the first and second p-i-n structures are operable in parallel. A multiplication region of the first p-i-n structure is to multiply charge carriers photogenerated within an absorption region of the second p-i-n structure with voltage drops between the shared first terminal and each of the second and third terminals being noncumulative.