Research led by a Duke Kunshan professor aimed at uncovering the physical properties of a semi-conductor material has advanced understanding of its potential technology uses.
Changcheng Zheng, associate professor of physics, and DKU undergraduates, examined how aluminium indium arsenide alloy reacts to light. They found certain characteristics of the material that could make it useful in developing optoelectronic devices, which detect and control light, and provided a quantitative foundation for further research.
“Our research forms the theoretical basis for important studies that could lead to improved optoelectronic technology with a range of uses from healthcare to communications,” said Zheng.
“We have expanded on research that looked at aluminium indium arsenide alloy and similar materials by quantifying the physical processes happening inside it to create a paper that can serve as a reference for further work.”
The research team shone a laser beam at a piece of aluminium indium arsenide alloy inside a low temperature optical chamber called a cryostat in order to test its reaction to light under different conditions. They looked specifically at two effects – localization and the photoluminescence processes of light excited electrons inside the material.
When light is shone onto most materials, subatomic particles called electrons absorb the energy from the light (photons) and jump to high energy states, in the process becoming free to move inside the material. In aluminium indium arsenide alloy, traps capture electrons in an effect called localization, preventing them from moving for a short period. When they do move, jumping back to a low energy state, they release photons, in a process called photoluminescence. A luminous watch, which shines under low light conditions, is an example of photoluminescence in action.
“When a beam of laser comes to the material, it will absorb some energy from it and then release another kind of light or photons,” said Zheng. “We then detect those photons, we study how they behave and from these photons we deduce the behavior of the electrons inside this material. It is the electrons that will impact the material’s applications.”
The researchers found that the quick capture and release of electrons by traps within the material made it a potential candidate for building fast infrared photodetectors. Infrared photodetectors react to light radiation and can be applied to a wide range of technologies including free-space communication (which uses light to wirelessly transmit data), surveillance, chemical sensing and biomedical imaging.
They also used a physical model to quantify the reactions taking place within the material, which allowed them to create a base for further research.
Working on the project with Zheng were Jiajun Yu and Yinan Zhao, who were undergraduate students majoring in materials science/physics at DKU.
Starting from little knowledge about the subject, Yu said the process was a steep learning curve that required “hard work and a good memory.”
“In the end I can say it was very beneficial as not only am I now skillful and well trained in this area, but also I learned how to conduct scientific research, which could be very useful in my future learning or research career,” she added.
Zheng’s team collaborated with several other Chinese universities on the research, including Nanjing University, ShanghaiTech University, Fudan University, Suzhou University of Science and Technology and Suzhou Institute of Nano-Tech and Nano-Bionics. Collaboration was particularly close with Nanjing University and ShanghaiTech University, said Zheng, who the DKU team formed a “research loop” with, each working on different aspects of investigation into aluminium indium arsenide alloy, from physical analysis to tech device design and testing.
