“We actually can make the curve any shape we like to fit the optical system,” said Professor Zhenqiang Ma. “Currently, there's no easy way to do that.”
The phototransistor has been produced using a ‘flip-transfer’ method, in which the final step is to invert the finished phototransistor onto a plastic substrate. At that point, a reflective metal layer is on the bottom.
“In this structure – unlike other photodetectors – light absorption in an ultrathin silicon layer can be much more efficient because light is not blocked by any metal layers or other materials,” Prof Ma noted.
The researchers also placed electrodes under the phototransistor’s silicon nanomembrane layer, allowing the metal layer and electrodes to act as reflectors and improve light absorption.
Ultimately, the new phototransistors open the door of possibility, he says.
"This demonstration shows great potential in high performance and flexible photodetection systems," Prof Ma concluded. “It shows the capabilities of high sensitivity photodetection and stable performance under bending conditions, which have never been achieved at the same time.”
