Nanowire Junction Crossing APD for Single Photon Detection
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Solution Overview
Problem
Existing photon detectors, such as photomultiplier tubes, are bulky, have limited linearity, low quantum efficiency, and are not well-suited for low-light applications or integration into system-on-chip platforms, and require high voltages, making them unsuitable for advanced imaging and LADAR applications.
Innovation Solution
The development of integrated circuit photon detectors using nanowire crossing regions to form avalanche photodiodes, which enable single photon detection with improved sensitivity and bandwidth by creating a junction crossing region between nanowires of different conductivity types, allowing for enhanced signal amplification and reduced dark count rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If photomultiplier tubes are used for photon detection, then high gain is achieved, but the device becomes bulky and requires vacuum tube technology
Solution Approach 1:
The photodetector is segmented into multiple nanowire components (first nanowire, second nanowire, third nanowire) that cross at a central region to form the active detection zone. This segmentation allows the device to achieve high gain through the nanowire junction structure while maintaining a compact form factor, eliminating the need for bulky vacuum tube photomultiplier tubes.
Solution Approach 2:
The invention transitions from planar photodetector designs to a three-dimensional nanowire crossing architecture. The nanowires extend in multiple dimensions (first nanowire in x-direction, second in y-direction, third in z-direction), creating a volumetric active region that increases detection efficiency and gain while reducing the overall device footprint.
2Reliability
If conventional photodetectors are used, then photon detection is achieved, but quantum efficiency is low
Solution Approach 1:
The photodetector employs composite nanowire structures with different semiconductor materials having different bandgaps. The first, second, and third nanowires are made of different semiconductor materials, allowing each to absorb specific wavelength ranges of incident light. This composite material approach increases overall quantum efficiency by capturing a broader spectrum of photons while maintaining a relatively simple nanowire crossing structure.
3Power
If photomultiplier tubes are used, then photon signal amplification is achieved, but the spectral response range is limited
Solution Approach 1:
The invention uses multiple nanowires composed of different semiconductor materials with varying bandgap energies. This allows the detector to respond to a broad spectral range from ultraviolet to infrared wavelengths. Simultaneously, the nanowire crossing junction provides signal amplification through avalanche multiplication, achieving both wide spectral response and signal amplification without the limitations of conventional photomultiplier tubes.
4Power
If high voltage is applied to photomultiplier tubes for gain, then internal detector gain is achieved, but the device requires complex high voltage power supply
Solution Approach 1:
The invention replaces the mechanical/electrical high voltage power supply system of photomultiplier tubes with a semiconductor-based avalanche photodetector structure. The nanowire crossing junction inherently provides avalanche multiplication gain when reverse-biased, eliminating the need for complex external high voltage power supplies and associated electronics, thereby reducing overall device complexity while maintaining high internal gain.
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
These nanowire-based detectors provide high sensitivity, sub-wavelength resolution, and improved spatial resolution, enabling effective low-light imaging and LADAR applications with reduced noise and increased efficiency compared to conventional detectors.
Implementation Method 1
The nanowire and the first semiconductor material form an avalanche photodiode (APD) in the junction crossing region to enable single photon detection
Implementation Method 2
The first nanowire has an intrinsic layer formed over the first semiconductor material to increase photon sensitivity
Data Source
AI summary
An integrated circuit includes a substrate material that includes an epitaxial layer, wherein the substrate material and the epitaxial layer form a first semiconductor material with the epitaxial layer having a first conductivity type. At least one nanowire comprising a second semiconductor material having a second conductivity type doped differently than the first conductivity type of the first semiconductor material forms a junction crossing region with the first semiconductor material. The nanowire and the first semiconductor material form an avalanche photodiode (APD) in the junction crossing region to enable single photon detection. In an alternative configuration, the APD is formed as a p-i-n crossing region where n represents an n-type material, i represents an intrinsic layer, and p represents a p-type material.