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Black Phosphorus Carbide Infrared Phototransistor for high speed and low light applications

Technology #2017-037

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Professor Ang Kah Wee
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Black Phosphorus Carbide Infrared Phototransistor for high speed and low light applications

Market Need

Photodetectors are a key component of many devices we use in our daily life. From metrology and imaging to optical communications, we rely on photodetectors to convert the information stored in light into electrical signals that can be processed by standard electronics. Due to its wide applications as a sensor in current technologies, it is therefore of great interest to find novel functional materials not only with high sensitivity, but also with wide absorption spectrum for more efficient detection at all wavelengths. Current commercial photodetectors based on three-dimensional (3D) material such as Silicon (Si) and Indium Gallium Arsenide (InGaAs), are opaque and brittle in bulk form, and thus are not a suitable sensor’s material for use in flexible optoelectronics in the coming age of the internet of things. Although photodetectors based on 2D materials are more flexible than bulk semiconductor, as of now, they do not show satisfactory performance in terms of gain and response time.


Prof Ang Kah Wee of the Department of Electrical and Computer Engineering has invented a high-performance composite few-layer b-PC phototransistor fabricated via a novel carbon doping technique, which achieved a high responsivity (R) of 2163 A/W, a short response time of 5.6 ps, a low shot noise equivalent power (NEPshot) of 1.3 fW/Hz1/2, and an intrinsic absorption  spectrum with non-zero absorption at 8000 nm all under ambient and room temperature conditions. The maximum responsivity of 2163 A/W and minimum response speed of 5.6 ps of the b-PC demonstrated here with our measurement setup is one of the highest in the literature, as shown in Figure 1 below, enabling it to be used for high speed and low light applications.

Figure 1: The maximum responsivity and minimum response time of b-PC phototransistor and other photodetectors reported in the literature. The values in bracket represent the applied bias voltage in volts and the excitation wavelength in nm.

Application and advantages

  • Possible applications are in optical power meters, RGB colour sensor for LCD backlight colour adjustment, sunlight sensors to control air flow for vehicle air conditioners, radiation detectors and surveillance systems
  • Fast response (5.6 ps) and high responsivity (2163A/W) for high speed and low light applications
  • Low shot noise equivalent power (NEPshot) of 1.3 fW/Hz1/2 for high sensitivity applications
  • Wide absorption spectrum ranging from visible light to infra-red regime


Phototransistor, black phosphorus carbide, infra-red, visible light

ILO Reference: 2017-037

Technology Readiness Level

TRL 3, material for testing, benchmarking, scalability testing.

Principal Inventor

Professor Ang Kah Wee (

Get in touch with Technology Manager

Tan Yan Ny

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Phone: + 65 6601 2812