Researchers at the University of California, San Diego (USCD), say they have discovered a new signal amplification process that may fuel new generations of electrical and photonic devices.

"For many years, the semiconductor industry has relied on photodetectors for optoelectrical conversion, followed by low-noise electronic amplifiers to convert optical signals into electronic signals with amplification to enable information detection and processing," says Yu-Hwa Lo, a professor of electrical and computer engineering at the University of California, San Diego.

However, impact ionization, a common choice for avalanche photodetectors, has many drawbacks, such as high operation voltage and loud noise during amplification. The UCSD research team searched for a more efficient intrinsic amplification mechanism for semiconductors in order to amplify the photocurrents with less noise and a lower voltage.

“Thanks to insights of the complex interactions among electrons in localized and extended states and phonons (a unit of vibrational energy that arises from oscillating atoms within a crystal), we’ve discovered a far more efficient mechanism – the cycling excitation process (CEP) – to amplify the signal,” Lo says.

According to the team, new improvements will allow the discovered signal amplification mechanism to be used in a wide variety of devices and semiconductors.

“With an efficient gain mechanism at an operation voltage compatible with CMOS integrated circuits, it’s possible to produce communication and imaging devices with superior sensitivity at a low cost,” Lo says. “By using other methods along with optical excitation to produce the seed carriers that initiate the cycling excitation process, we can conceive new types of transistors and circuits and extend the scope of applications beyond optical detection.”

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