The Benefits of Customizing Your Photodetector

Table of Contents

Overview
Photodetector Materials and Characteristics
Photodetector Wavelengths
Marktech Photodetector Variations
     Silicon Photodetectors (400 nm to 1100 nm)
Silicon Avalanche Photodiodes (400 nm to 1100 nm, optimized for 800 nm and 905 nm)
UV Detectors (150 nm to 570 nm)
     UV-A
     Typical Industries Served
     Common Applications
InGaAs PIN Photodetectors (800 nm to 2600 nm)
Short Wavelength IR (SWIR) Emitters (1050 nm to 1720 nm)
     SWIR for Night Vision Applications
SWIR Detector for Homeland Security Applications
     Applications in Medical and Biophotonics
SWIR Industrial Applications
     SWIR Applications in Agriculture
     LIDAR Applications

Overview

Photodetectors are sensors that detect light and convert the photons into measurable currents, and hence they are useful for a wide range of applications from water faucets to nuclear transient events. Specific measurements that are ideal for customers’ applications can be made with various technologies and packaging.

Marktech offers only solid-state devices; there are no photomultiplier tubes in the company’s product line, although the products may deliver similar functionality. Response rates can be as fast as 300 picoseconds. Light levels that are measurable range from tens of photons to massive levels. Wavelengths can range from 150 nm to more than 3000 nm.

Each photodetector uses p-n or n-p junctions as part of either a phototransistor or photodiode construction, effectively operating as an inverse function from the typical operation of a light emitting diode. The detectors provide current response to particular ranges of light wavelength, depending on the technology used.

Photodetector Materials and Characteristics

The materials, such as silicon, GaP or InGaAs can be used. The N and P epitaxial layers of the wafer materials can be optimized for particular customer specifications and required characteristics, including Optimized Responsivity low dark current, minimum reflection, low cross talk, minimum series resistance, fast response, low capacitance and more. The detectors can be packaged in a wide range of packages from metal can and standard 3 mm and 5 mm plastic packages, to surface-mount or virtually any custom package assembly. Detector applications range from simple door opening to the latest cancer PET scan system.

Photodetector Wavelengths

Products available have wavelengths ranging from 150 nm (UV) through the visible range (440 to 700 nm), through short wavelength infrared (SWIR) up to 2600 nm, and beyond to medium wavelength IR (MWIR) (>3000 nm). Marktech’s online Product Selector Guide can help customers select the emitter wavelengths and can also indicate compatible detectors. Marktech’s tight binning can provide uniform wavelength characteristics to improve the application and the sensitivities of mating detectors, and provide process-controlled and uniform product solutions.

Marktech Photodetector Variations

  • Silicon avalanche photodiodes (400 nm to 1100 nm, with 800 nm and 905 nm optimization)
  • Silicon photodetectors (400 nm to 1100 nm): photovoltaic, phototransistors, and photoconductive photodiodes
  • InGaAs PIN photodetectors (800 nm to 2600 nm) and short wavelength IR (SWIR) detectors (1050 nm to 1720 nm)
  • UV detectors (150 nm to 450 nm)

Products are also offered in epitaxial wafer form, and can be packaged as arrays, photoreflectors and hybrid parts.

Silicon Photodetectors (400 nm to 1100 nm)

The silicon phototransistors available from Marktech can be utilized in applications that require uniform response, very high sensitivity and increased reliability such as optical sensors and card readers.

The photovoltaic silicon photodetectors have a spectral sensitivity from near-ultraviolet, through to the visible range, to short wavelength infrared (SWIR) (400 nm to 1100 nm). These photodetectors are used in applications such as spectroscopy equipment, analytical, medical, communications and sensing requiring broadband sensitivity with improvements in the blue/green region. These devices can exhibit high sensitivity, low noise and moderate-speed response. These silicon photodetectors are available as either photodiodes or phototransistors

The photoconductive silicon photodetectors are ideal for high-sensitivity and high-speed applications. The spectral range extends from 400 nm to 1100 nm and makes these photodiodes suitable for visible and near-IR applications, including AC applications such as detection of LEDs and pulsed LASER sources.

The broad line of silicon photodetectors from Marktech are offered in different package types, including through-hole plastic, metal-can, surface mount, ceramic and full custom. These devices are supplied with standard silicon die with a spectral sensitivity of about 400 nm to 1100 nm, or with special UV-enhanced silicon chips having sensitivity in the lower UV-A range. In addition, custom active areas and multi-element chips can be developed to suit customers’ application. Most of the company’s wafers/chips are produced in the USA and are optimized to insure consistent and uniform performance with high reliability. These devices are suitable for visible and near-IR applications that require high sensitivity, high speed and low noise such as optical communications and optical switches.

Marktech silicon detectors can be obtained with built-in filters for reduced visible light interference or optimized to suit the required spectral output of customers. In addition to several package styles available off-the-shelf, Marktech can incorporate various detectors and/or emitter detector combinations in a single package type.

Silicon Photodetector Variations

  • Avalanche Photodiodes
  • Differential photodiodes
  • Dual/quadrant photodiodes
  • Multichip photodiodes for expanded wavelength or sensitivity
  • Photodiode arrays
  • Silicon photodiode arrays
  • Silicon phototransistors
  • Silicon photovoltaic PIN photodiodes
  • Silicon photoconductive PIN photodiodes
  • Silicon PIN photodiodes with enhanced blue sensitivity
  • Silicon photodiodes in SMT, through-hole DIL and metal can packaging
  • X-ray detectors

Customized Optimizations

  • 1064 nm, 2200 nm and 2600 nm
  • UV blue-green NIR (near-IR)
  • Low dark current
  • Fast response
  • Low capacitance
  • Low cross-talk
  • Low carrier lift time
  • Minimum reflection
  • Minimum series resistance

Customized Packaging

  • Chips
  • Tested wafers
  • Detector/filter combinations (bandpass or color glass)
  • Hermetic packaged devices
  • Hybrid/modules (ceramic or COB [chip on board])
  • Hybrids (detector/amplifier in one package)

Typical Industries Served

  • Optical communications
  • Medical
  • Industrial
  • Scientific
  • Analytical

Common Applications

  • Optical encoders
  • Fiber optics
  • Barcode readers
  • Remote controls
  • Position sensors
  • Chemical analysis

Silicon Avalanche Photodiodes (400 nm to 1100 nm, optimized for 800 nm and 905 nm)

Ideal for low-light level and high-speed detection in the near-infrared range, avalanche photodiodes have become the semiconductor equivalent of photomultipliers in various applications, including LIDAR, instrumentation, photon counting and data communication. Furthermore, cost-effective customization of these APDs is provided to meet the compelx design specifications. Various other application specific solutions, including wavelength-specific band-pass filtering, operation voltage selection and voltage breakdown (Vbr) binning and hybridization options, are available at Marktech.

Marktech APDs have a fast time response, internal gain mechanism, high sensitivity and low dark current in the near-infrared region. These APDs are recommended for applications that need high bandwidth or where internal gain is required to overcome high pre-amp noise. Marktech APDs also provide higher sensitivity compared to a traditional photodiode and are ideal for short pulse detection and extreme low-light level detection. APDs are basically photodetectors that provide an amplification gain stage using avalanche multiplication. Though APDs are similar to photomultipliers, they are solid-state semiconductor devices.

Silicon Avalanche photodiodes (Si APDs) are the ideal optical detectors for applications where the wavelength ranges from 400 nm to 1100 nm (with 800 nm and 905 nm optimized sensitivities), and display low noise and high speed for visible to near-IR applications. Standard versions are supplied in three active area diameter sizes: 200, 500, and 800 um, and are available in hermetic TO cans and can also be delivered in cost-effective LCC packages.

UV Detectors (150 nm to 570 nm)

UV LEDs are becoming more common in the industry and replace old technology such as mercury lamps. Therefore, the demand for UV detection is also growing. Marktech offers UV detectors in a variety of TO metal can-type packages from TO-18 to TO-39 with a special UV glass lens to guarantee optimum lifetime and the least amount of material degradation. The company also provides both standard and custom packaging including assemblies, components and bare chip options to meet the application requirements of customers.

Marktech’s UV detectors use materials including GaN, SiC and GaP Schottky. A die can be packaged separately in a wide range of hermetically sealed packages or multiple die can be included in a custom package to suit customers’ specific application. These UV detectors provide high device sensitivity with low dark current and better stability over time.

UV-A

Marktech also supplies silicon-based UV detectors that are designed for operation in the UV-A range on a custom basis. These devices are offered in plastic and surface mount packages besides the standard TO metal can-type.

Typical Industries Served

  • Medical
  • Environmental/Ecological
  • Industrial
  • Scientific and Analytical
  • Commercial

Common Applications

  • UV emitter output monitoring
  • Outdoor UV sensors
  • Gas/flame detection
  • Biomedical/Chemical analysis
  • Spectrometers and wearable devices
  • Emitter calibration
  • UV dosimetry and imaging including solar UV measurements and Astronomical studies
  • Flame sensors (fire alarm systems, missile plume detection, combustion engine control)
  • Spatial Optical Communications (intra- and inter-satellite secured communications)
  • Biological and Chemical sensors (ozone detection, determination of pollution levels in air, and biological agents detection).

InGaAs PIN Photodetectors (800 nm to 2600 nm)

InGaAs PIN Photodetectors are highly reliable and highly sensitive products that are well-suited for applications in the SWIR (short wavelength infrared) wavelength range. These highly reliable and highly sensitive products are ideally suited for optical communication devices.

Photodiode chip active area sizes ranging from 0.1 mm to 3.0 mm are available to offer the best balance between high speed, light sensitivity and low dark current. This allows for improved flexibility and options in a wide range of applications, from high-speed optical communications and fiber optics to medical and chemical analysis.

Currently, integrated TE (thermal electric) cooling is not cuurently utilized on the company’s standard PIN photodiodes, thereby reduing costs and improving overall efficiency.

Besides PIN photodiodes, Marktech provides foundry services for epitaxial growth of SWIR wafers in the 1.0 um to 2.6 um range, using InP material as the base substrate. The company is currently manufacturing these highly reliable wafers in 2”, 3”, and 4” diameters. These wafers are used for a variety of applications including photodetectors, image sensors and linear arrays. Photodetectors developed using the company’s epitaxial wafers provide considerable advantages, including better shunt resistance, lower dark current and overall enhanced performance at lower operating temperatures.

Marktech produces InP PIN photodiodes with InGaAs/InP technology, which have a spectral sensitivity in the 800 nm to 2600 nm range for applications that require high speed, low dark current and high sensitivity such as optical communications and fiber optics. The detector die supplied by Marktech can be placed in a wide range of packages from metal can TO-5, TO-18 and TO-46 to surface mount and standard 3 mm and 5 mm plastic packages. Marktech can also integrate the detector die in custom-designed assemblies.

Short Wavelength IR (SWIR) Emitters (1050 nm to 1720 nm)

Marktech Optoelectronics is one of a few manufacturers that provide emitters in the SWIR or extended wavelength range. Its standard product offering includes surface mount and through-hole packages with wavelengths ranging from 1050 nm to 1720 nm and operating currents ranging from 20 mA to 350 mA for high-power applications. The company also offers higher wavelength ranges up to 3000 nm for specific package types.

Since traditional silicon detectors have a maximum sensitivity limit of up to approximately 1100 nm, the SWIR wavelength range needs specialized optical detectors. Marktech manufactures a range of InGaAs detectors that are improved for sensing light in the SWIR wavelength range. These detectors can be obtained as a separate and discrete component, or they can be combined with a silicon sensor in order to cover the full spectrum of light from the visible to the SWIR range. The company also provides the option to custom-produce multi-element devices with emitter and detector chips in the same package.

Marktech’s extended wavelength standard SWIR package offerings include:

  • TO-46 lens
  • TO-46 flat
  • SMD 1206
  • SMD 1206 lens
  • TOPLED PLCC4
  • SMD high-power black

Marktech’s optoelectronic manufacturing and assembly capabilities include:

  • High-density pick and place
  • SMD, through-hole and chip on board assembly
  • PCB design and fabrication
  • Prototyping
  • Schematic capture
  • CAD/CAM
  • In-circuit testing
  • Reliability testing
  • Conformal coating
  • Potting
  • Simulation
  • Small to high volume production runs
  • Single or multi-layer
  • Aluminum, FR4, ceramic and polyimide
  • Flexible or rigid
  • PCB design
  • Consigned or purchased materials
  • IPC standard assembly
  • Use of customers' part numbering system
  • Shipped to customers' packaging requirements

Additional outsourced capabilities include:

  • Optical analysis
  • Thermal analysis
  • Metal work fabrication
  • Plastic injection molding

Photodetector Applications

  • Automotive: Driver vision in low light, twilight detection and collision detectors
  • Astronomy: Space-based telescopes with far-IR wavelengths
  • Chemical/Biological: High-speed detection
  • Communication: Fiber optic communication (typically operates in infrared wavelength) with very high rise time (response rate) to enable high data rates of up to 100 Gbps, long wavelength systems used in InGaAs (indium gallium arsenide) detectors as they have lower noise compared to germanium (which enables for more sensitive receivers), silicon photodiodes used for short wavelength links (650 for POF and 850 for glass MM fiber) and very high speed systems using avalanche photodiodes (APDs) that are biased at high voltage in order to create gain in the photodiode
  • Banking: Counterfeit detection in currency
  • Consumer: Household electronics (TVs, radios, DVD players, computer sensors) and cameras
  • Medical: Pulse oximeters, PET and CAT scans
  • Municipal: Monitoring of water purification for municipal water supply, pools
  • Military: Night vision applications, and intake/exhaust temperatures for aerospace
  • Safety/Security: Smoke/flame detection and TSA security
  • Industrial: Robotic imaging/sensing, process control through temperature monitoring, video camera imaging, bar coding, and arc light detection (ultraviolet wavelength detectors are offered in applications where UV LEDs and mercury lamps are used)
  • Environmental: Detection through spectroscopy for pollutants and particulates, thermal imaging for business and home heat loss/efficiency, global temperature monitoring through space-based sensors and recycling (material identification from fluorescence of plastics/glass)

SWIR for Night Vision Applications

SWIR detectors have been employed in SWIR night vision systems, which depend on the intense night glow that can light up the scenery even when there is total darkness in the visible spectrum.

SWIR Detector for Homeland Security Applications

Applications in Medical and Biophotonics

SWIR detectors can help achieve the non-invasive imaging methods. For instance, optical coherence tomography (OCT) systems uses SWIR to exploit the low scattering properties of >1 µm light to view the previously inaccessible, thick parts of the eye’s cornea.

SWIR Industrial Applications

Inspection for High-Temperature Manufacturing Processes: Web inspection of continuous processes such as high-temperature manufcturing and quality controls.

Recycled Plastics Resorting Application: SWIR can be employed in the recycled plastics industry due to N-H, C-H, and O-H, found in plastics, and uses wavelength ranging from 1.0 to 2.2 µm.

SWIR Applications in Agriculture

When combined with visible detectors, SWIR detectors, such as 1240 nm, 1640 nm, and 2130 nm, can be used in some remote sensors for agricultural drought and soil moisture monitoring.

Compared to visible images, SWIR imaging can provide more information about soil and rock owing to the reflection characteristics of soil and rock in the 1.8 um to 2.5 um range.

LIDAR Applications

Light detection and ranging (LIDAR) is a surveying method used for measuring a distant target by illuminating that target with a pulsed laser light. LIDAR uses laser light pulses, whereas radar uses radio waves. Avalanche photodiodes allow the LIDAR application as a remote sensing technology that optically measures scattered light properties to find range and/or other information relating to a distant target.

This information has been sourced, reviewed and adapted from materials provided by Marktech Optoelectronics.

For more information on this source, please visit Marktech Optoelectronics.

Ask A Question

Do you have a question you'd like to ask regarding this article?

Leave your feedback
Submit