Photocurrent generation in Ge nanocrystal/Si systems

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Semiconductor nanocrystals offer tunable electronic and optical properties.
• Germanium (Ge) nanocrystals are explored for their potential in electronic and optoelectronic devices.
• Silicon (Si) substrates provide a robust platform for integrating nanostructures.

Purpose of the Study:

• To investigate photocurrent generation in devices utilizing Ge nanocrystals.
• To determine the influence of Ge nanocrystal size on device performance.
• To correlate device efficiency with the optical absorption properties of Ge.

Main Methods:

• Fabrication of planar devices with Ge nanocrystals on a n-doped Si(001) substrate.
• Deposition of a 5 nm thermally grown SiO2 layer.
• Measurement of photocurrent and Incident-Photon-to-electron Conversion Efficiency (IPCE).

Main Results:

• Successful generation of photocurrent in the visible and ultraviolet range.
• IPCE spectral range demonstrated a dependence on Ge nanocrystal size.
• Increased IPCE values in the 350-600 nm range correlated with Ge absorbance.

Conclusions:

• Ge nanocrystal/SiO2/n(+)-Si devices exhibit photocurrent generation capabilities.
• Device performance, specifically IPCE, is tunable by controlling Ge nanocrystal size.
• The findings support the use of Ge nanocrystals in optoelectronic applications.