Quantum Dot ToF Sensor Layout for Low Dark Current SWIR Sensing
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Solution Overview
Problem
Time-of-flight sensors using bulk semiconductor materials face challenges with high dark current at room temperature and limitations in the short-wave infrared frequency band, particularly with silicon-based sensors.
Innovation Solution
A time-of-flight sensor design featuring a light emitter and signal reception sensor array based on semiconductor nanoparticles, separated by an optical barrier, with a reference sensor using InSb, InAs, or InAsSb layers, and incorporating hole and electron transport layers, and partially transparent conductive layers to optimize performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If bulk semiconductor materials like silicon are used to build single photon avalanche diodes, then the receiver sensors can be manufactured with established processes, but the dark current is high at room temperature
Solution Approach 1:
The patent changes the material parameter from bulk semiconductor to semiconductor nanoparticles (quantum dots), which fundamentally alters the electronic structure and reduces dark current through quantum confinement effects while maintaining manufacturability through colloidal processing techniques
Solution Approach 2:
The patent employs composite material structures combining semiconductor nanoparticles with appropriate matrix materials and device architectures, creating a hybrid system that leverages the quantum properties of nanoparticles while maintaining the structural advantages of bulk materials
2Temperature
If bulk semiconductor materials are used, then the sensors can operate at room temperature, but the performance is limited in the short-wave infrared frequency band
Solution Approach 1:
The patent adjusts the bandgap parameter of the semiconductor material by changing from bulk to nanoparticle form, enabling tuning of the optical response to match short-wave infrared wavelengths while maintaining room temperature operation through appropriate material composition and size selection
3Object-generated harmful factors
If the signal reception sensor array is separated from the light emitter by an optical barrier, then direct light contamination is prevented, but the device complexity increases
Solution Approach 1:
The patent introduces an optical barrier as an intermediary element between the light emitter and signal reception sensor array, which mediates the optical interaction by blocking direct light paths while allowing reflected light to reach the sensors, thus eliminating contamination without requiring complex mechanical shielding or active cancellation systems
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 design reduces dark current and enhances sensitivity in the short-wave infrared range, improving the accuracy and efficiency of time-of-flight measurements while minimizing energy consumption.
Implementation Method 1
the reference sensor and the signal reception sensor array are based on semiconductor nanoparticles
Implementation Method 2
the optical barrier being configured to prevent light emitted by the light emitter from directly reaching the signal reception sensor array
Data Source
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AI summary
The present disclosure relates to a time-of-flight sensor, ToF (100) comprising, on a same base substrate (122), a light emitter (108) emitting light (118) into an image scene (50), a reference sensor (106) detecting light emitted by the light emitter (108), and a signal reception sensor (104) array separated from the light emitter (108) by an optical barrier (126), the optical barrier (126) preventing light emitted by the light emitter (108) from directly reaching the signal reception sensor (104) array, the signal reception sensor (104) array detecting light (124) reflected by the image scene (50), wherein the reference sensor (106) and the signal reception sensor (104) array are based on semiconductor nanoparticles. The optical barrier (126) is arranged between the upper surface (114) of the base substrate (122) and an inner surface of a packaging unit (102). The base substrate (122) may also comprise a control circuit (112). Alternatively, a device substrate comprises the control circuit (112). The semiconductor nanoparticles can be quantum dots, quantum wires, quantum rods, or quantum wells. The light emitter (108), which may be a vertical-cavity surface-emitting layer, VCSEL, may also be based on semiconductor nanoparticles. The semiconductor nanoparticle layer or layers of the reference sensor (106), of the signal reception sensor (104), and of the emitter (108) are for example formed of InAs or InSb or InAsxPx or InAsxSbx. The device (100) is for example implemented under a touch display screen of a mobile communication device.