Making strides in quantum dot infrared photodetectors

June 5, 2007

Researchers at Northwestern University have made significant strides in the development of quantum dot infrared photodetectors -- technology that may provide new imaging techniques with applications in medical and biological imaging, environmental and chemical monitoring, night vision and infrared imaging from space.

Conventional infrared photon detector technology for imaging applications typically requires that the detector be cooled to very low temperatures -- approximately 77 degrees Kelvin. This cooling requirement adds significant cost, bulk and power consumption to the imaging systems, therefore limiting their usability. By using nanotechnology to form quantum dots, researchers at Northwestern's Center for Quantum Devices (CQD) are one step closer to achieving the goal of developing high-performance imaging techniques that can operate at higher temperatures.

Quantum dots, also known as "artificial atoms," have been widely investigated as a means of improving a variety of electronic and optoelectronic devices. The small size of quantum dots, usually around 10 nanometers, gives them a unique physical property of three-dimensional confinement, which can enable higher operating temperatures when used in infrared detector design.

"The development of an infrared photon detector that can operate at higher temperatures will enable the use of cheaper, lighter and more efficient cooling methods in the design of infrared imaging systems," said Manijeh Razeghi, Walter P. Murphy Professor of Electrical Engineering and Computer Science and director of the Center for Quantum Devices. "This will allow the use of infrared detectors in a much wider range of applications."

Researchers at CQD made a great breakthrough in the development of high-performance quantum dot infrared photodetectors (QDIP). They have developed a QDIP that operates at room temperature with a peak detection wavelength in the technologically important middle wavelength infrared window -- wavelengths between three and five microns are important because they are not susceptible to absorption by Earth's atmosphere. The QDIP is based on a hybrid indium arsenide quantum dot and an indium gallium arsenide quantum well structure grown on an indium phosphide substrate.

The specific detectivity and quantum efficiency at 150 degrees Kelvin were 4×1010 cmHz1/2/W and 35 percent, respectively. This record high performance was published in the March 26, 2007, issue of Applied Physics Letters, Vol. 90 No. 13. In devices developed since publication, the performance was further improved with a quantum efficiency of 48 percent through the optimization of the quantum dot growth, which led to stronger infrared absorption.

Source: Northwestern University

Explore further: Radiation technique could offer less harmful alternative to X-rays

Related Stories

Fluorescent dye could enable sharper biological imaging

April 9, 2018

Fluorescence imaging is widely used for visualizing biological tissues such as the back of the eye, where signs of macular degeneration can be detected. It is also commonly used to image blood vessels during reconstructive ...

Plasmons triggered in nanotube quantum wells

March 16, 2018

A novel quantum effect observed in a carbon nanotube film could lead to the development of unique lasers and other optoelectronic devices, according to scientists at Rice University and Tokyo Metropolitan University.

Researchers observe the switching of Ras protein in detail

March 21, 2018

Ras proteins are molecular switches that decide if and when cells divide inside our bodies. An impairment of their function may result in the formation of a tumour. The process of switching the proteins on and off has been ...

Recommended for you

Observing cellular activity, one molecule at a time

May 21, 2018

Proteins and molecules assemble and disassemble naturally as part of many essential biological processes. It is very difficult to observe these mechanisms, which are often complex and take place at the nanometer scale, far ...

A soft solution to the hard problem of energy storage

May 18, 2018

It's great in the lab, but will it actually work? That's the million-dollar question perpetually leveled at engineering researchers. For a family of layered nanomaterials, developed and studied at Drexel University—and ...

New blood test rapidly detects signs of pancreatic cancer

May 17, 2018

Pancreatic cancer is expected to become the second deadliest cancer in the United States by 2030. It is tough to cure because it is usually not discovered until it has reached an advanced stage. But a new diagnostic test ...

Metallic drivers of Alzheimer's disease

May 17, 2018

X-ray spectromicroscopy at the Scanning X-ray Microscopy beamline (I08), here at Diamond, has been utilised to pinpoint chemically reduced iron and calcium compounds within protein plaques derived from brains of Alzheimer's ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.