Quantum dot photodetector features graphene
Two research groups at Barcelona’s Institute for Photonic Sciences (ICFO) have collaborated to make a hybrid photodetector incorporating both graphene and quantum dots.
Although the two material technologies are both at an early stage of development, the team claims that the combination could lead to fast, efficient, and low-cost devices capable of detecting across the visible, near-infrared and short-wave infrared (SWIR) spectral regions to a wavelength of around 3 µm.
At the moment, high-efficiency photodetection in the SWIR region beyond 1 µm tends to rely on indium gallium arsenide (InGaAs) devices, which although produced in large volumes rely on high-precision manufacturing techniques and are relatively expensive as a result.
Writing in the open-access journal Nature Communications, the team led by ICFO professors Frank Koppens and Gerasimos Konstantatos describe the performance of a lead-sulfide (PbS) colloidal quantum-dot (CQD) photodiode on top of a graphene phototransistor.
They reported a peak spectral response at 1.6 µm, although that absorption peak can be tuned by altering the size of the CQDs when they are synthesized.
“Our hybrid detector overcomes the limitations of a phototransistor in terms of speed, quantum efficiency and linear dynamic range,” wrote the team, pointing to quantum efficiencies in excess of 70 per cent, and a gain of 105.
“This hybrid architecture finally illustrates the potential of graphene and other two-dimensional materials to be successfully integrated with other optoelectronic materials and open new ways for hybrid two-dimensional/zero-dimensional optoelectronics,” they conclude.