Controllable, Self-Powered, and High-Performance Short-Wavelength Infrared Photodetector Driven by Coupled Flexoelectricity and Strain Effect

This paper has demonstrated that the flexoelectric effect drives a giant infrared (λ ≤ 1800 nm) photoresponse in centrosymmetric bulk silicon that extends far beyond the fundamental bandgap (λ = 1100 nm) is demonstrated. Notably, the device has a large on/off ratio (≈105), exceptionally high sensitivity (2.5 × 108%), a good responsivity of 96 mA W−1, decent specific detectivity of ≈1.54 × 1014 Jones, and a rapid response speed of ≈100 µs, even at nanoscale (<30 nm), are measured at λ = 1620 nm. It increases the sensitivity of the infrared response (up to 1.4 × 108%) by controlling the pointed force. These findings demonstrate the possibility of achieving tunable optoelectronic performance beyond the fundamental limit of mechanoelectrical coupling and have various innovative uses, including mechanoptic switches, photovoltaics, sensors, and self-driving cars.

Table Of Contents

Overview-

  • In centroymmetric materials, mechanical deformations can generate polarization fields and strain gradients with flexoelectric functionalities, such as flexo-photovoltaic effects. 
  • Nanoscale/micrometer-scale inhomogeneous strain can reorganize the electronic arrangements, which, of course, changes the limits of optoelectronics as well. 

Study design-

  • Commercially available n-type silicon (resistivity = 1 – 10 Ω cm, from science tech Wafer) was used to test the behavior of applied force.
  • The silicon was supported by a hard surface to prevent it from breaking.
  • Silicon wafers were cleaned with nitrogen gas and dried before measurements.
  • To remove the native oxide, silicon was etched with buffered HF solution for five minutes.
mohit 1

Image Source- Wiley Online Library

Key Findings-

  • A self-biased short-wavelength infrared photoresponse (λ ≤ 1800 nm) was demonstrated from bulk silicon due to the flexoelectric effect.
  • The device shows applied force-dependent tunable photo-sensing performance at 1620 nm with a high on/of ratio of ≈105, sensitivity (2.5 × 108%), responsivity (96 mA W−1), a decent specific detectivity (1.54 × 1014 Jones).
  • A change in the silicon’s effective bandgap may be a consequence of localized force-induced long-range distributed inhomogeneous strains.
  • By photoconductive atomic force microscopy, it has been shown that the flexoelectric effect drives photoresponse and it can be tuned.
  • We can directly observe the flexoelectric effect-driven photoresponse and its tunability using photoconductive atomic force microscopy.
  • It opens the way to flexoelectronic-driven optoelectronic functionality in centrosymmetric semiconductors, paving the way for local polarization field-controllable electronics and high-performing optoelectronic applications.

Generalized Results-

  • As a result of photoconductive atomic force microscopic measurements, the flexoelectric effect is directly linked to photoresponse and its tunability.
  • Through the use of the flexoelectric effect, photon sensing can be extended way beyond the fundamental bandgap of silicon.

Future Work Perspectives-

  • This approach shows how mechanoelectrical coupled tunable optoelectronic performance can be achieved beyond the fundamental limit.
  • Mechanoelectrical coupled tunable optoelectronic can be effectively applied to mechanoptical switches, photovoltaics, sensors, and self-driving vehicles.

Conclusion

This approach shows how mechanoelectrical coupled tunable optoelectronic performance can be achieved beyond the fundamental limit and how it can be effectively applied to mechanoptical switches, photovoltaics, sensors, and self-driving vehicles.

Controllable, Self-Powered, and High-Performance Short-Wavelength Infrared Photodetector Driven by Coupled Flexoelectricity and Strain Effect

Research Paper Detail in PDF

About the author

About the Author
More Detail

Dr. Mohit Kumar

  • Ajou University, South Korea

Dr. Mohit Kumar is working as Professor at Ajou University, South Korea. Ph.D. from the Institute of Physics, Bhubaneswar, then Postdoc from Weizmann Institute of Science, Israel, INU, South Korea, and currently in Ajou University, South Korea.

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