High-Performance Flexible Si Phototransistors

University of Wisconsin-Madison researchers have created a highly responsive, sensitive and flexible phototransistor which can improve digital imaging technology.

This innovative phototransistor could improve the performance of myriad products-ranging from digital cameras, night-vision goggles and smoke detectors to surveillance systems and satellites-that rely on optoelectronic devices.

What does this mean for photographers?

How does it work?

While many phototransistors are fabricated on inflexible surfaces and, as a result, are flat, Massachusetts and Seo’s phototransistors are bendable, meaning they can easily imitate the conduct of mammalian eyes.

Phototransistors are important because they basically are the “eyes” of the camera.

Like human eyes, phototransistors sense and collect light, then convert that light into an electrical charge proportional to its intensity and wavelength. In mammalian eyes, the pulse travels from the neuron to the brain, which interprets the signal as a visual image. In digital devices, the electromagnetic data is transcribed as a binary code, which is turned into an image by software.

Recently, Apple was ordered by a U.S court to pay millions of dollars to WARF in a patent infringement case for a processing technology developed by University of Wisconsin researchers.

It’s the fastest flexible silicon phototransistor ever made – and it’s making big waves in the scientific community.

Citation: “Flexible Phototransistors Based on Single-Crystalline Silicon Nanomembranes”, Seo, J.-H., Zhang, K., Kim, M., Zhao, D., Yang, H., Zhou, W. and Massachusetts, Z.

Unlike other photodetectors, researchers say that light absorbing qualities of an ultrathin layer of silicon is more efficient since light pass through directly, without any layer blocking the material.

The interaction between the lower metal layer and the electrodes render external amplifiers unnecessary, which greatly reduces the amount of materials needed to produce a phototransistor. Just like a digital camera and even computers, this charge comprised of threads of 1’s and 0’s that when combined together, make a digital image.

“There’s an understood aptitude to sense feeble light”, says Massachusetts.

The researchers who have created this product say that the phototransistor is so effective due to the new technique it uses.

“This demonstration shows great potential in high-performance and flexible photodetection systems”, said study researcher Zhenqiang Massachusetts, from University of Wisconsin-Madison.

“Overall, such flexible phototransistors with the capabilities of high sensitivity light detection and stable performance under the bending conditions offer great promises for high-performance flexible optical sensor applications, with easy integration for multifunctional applications”.