Recent improvement of silicon absorption in opto-electric devices

As an integral part of all electronic devices, silicon plays an important role in opto-electronic devices such as photodetectors and photovoltaic devices. However, since Si is an indirect band-gap material, phonon assistance is required in the photo-excitation process to compensate the wave-vector difference between the valence band maximum and the conduction band minimum, respectively. As a result, Si is a poor absorber of light, which decreases the efficiency of Si-based opto-electronic devices. The poor absorption in the telecommunication wavelength range hinders wider applications of Si-based opto-electronic devices.

Prof. Takashi Yatsui from University of Tokyo is dedicated to the research of integrated opto-electronic devices. He systematically reviews the recent studies on improving the optical absorption performance of Si in Opto-Electronic Advances. A summary of recent theoretical approaches based on the first principle calculation to enhance the optical absorption of Si has been provided. It is followed by an overview of recent experimental approaches including scattering, plasmon, hot electron, and near-field effects. More details of a practical photodetector with p-n junction and Au nanoparticles are discussed. At the end, Prof. Takashi Yatsui proposes a perspective on the future research direction of Si-based photodetectors and photovoltaic devices.

About The Group

The Yatsui group is focused broadly on light-mater interaction at the nanoscale, harnessing the unique physical properties of optical field to realize various novel photonic systems including the following topics:

1) high performance opto-electric device

2) nanophotonic fabrication to realize atomically flat surface

3) sustainable development applications including water splitting, artificial photosynthesis

4) highly magnetic sensitivity in magnetometer using nitrogen-vacancy center in a bulk diamond


Yatsui T. Recent improvement of silicon absorption in opto-electric devices. Opto-Electron Adv 2, 190023 (2019).