Researchers from the China University of Petroleum have developed a new infrared photodetector based on a nanoporous ZnO/n-Si structure, according to a report published in Science China: Physics, Mechanics & Astronomy.
The photodetector is based on zinc oxide (ZnO), which is an environmentally friendly semiconductor that is well-known for effectively absorbing UV light because of its wide bandgap. When the researchers combined ZnO with n-type silicon (n-Si) in a nanoporous structure, it showed a unique photoresponse when subjected to near-infrared pulsed light irradiation.
The nanoporous structure is synthesized by a simple sol-gel method, the researchers said.
Firstly, the scientific team exposed the nanoporous structure to a 1,064 nanometre wavelength laser pulse with energy of 0.072 mJ, which produced two different peaks—a higher photovoltaic peak with an amplitude of ~ 235 mV and a lower photovoltaic peak with an amplitude of ~13 mV.
They subsequently increased the energy of the laser pulse to 0.332 mJ, which in turn lifted the higher photovoltaic peaks to ~ 275 mV but triggered no change in the lower photovoltaic peak. The time interval between the higher and the lower peaks proved very sensitive to changes in the energy of the laser pulse.
The researchers said that illumination of one infrared laser pulse led to the porous structure showing a double peak on a millisecond time scale in the decay of transient photovoltage.
The ZnO/n-Si structure has the potential to produce a simpler, low-cost detector for an infrared pulsed laser. Photodetectors already find application in many optoelectronic devices, some examples being night vision goggles and digital cameras.
The study was funded by the National Key Basic Research Program of China, the Program on National Key Scientific Instruments and Equipment Development, the Beijing National Science Foundation and the Science Foundation of the China University of Petroleum.