The Co-film-thickness dependent lateral photoeffect in Co-SiO2-Si metal-oxide-semiconductor structures

Area of Science:

• Materials Science
• Solid-State Physics
• Nanotechnology

Background:

• Metal-semiconductor junctions are crucial for electronic devices.
• Photoelectric effects in thin films are of significant research interest.
• Understanding lateral photoeffects can lead to novel sensor applications.

Purpose of the Study:

• To investigate the transient lateral photoeffect (LPE) in thin cobalt films on n-type silicon.
• To analyze the dependence of the lateral photovoltage (LPV) on laser position and film thickness.
• To elucidate the underlying mechanisms governing LPE in this system.

Main Methods:

• Deposition of thin metallic cobalt films onto n-type silicon substrates with native silicon dioxide surfaces.
• Non-uniform irradiation of the cobalt film using a laser beam.
• Measurement of the lateral photovoltage (LPV) as a function of laser beam position.
• Systematic variation of cobalt film thickness.

Main Results:

• A transient lateral photoeffect (LPE) was observed in cobalt films on silicon.
• The lateral photovoltage (LPV) exhibited high sensitivity to the laser position within the metal film plane.
• LPV showed a significant dependence on cobalt film thickness, with peak sensitivity of 42.6 mV/mm for a 2.8 nm film.
• Sensitivity decreased substantially with increasing film thickness due to a shorting effect.

Conclusions:

• The observed LPV is attributed to the metal-semiconductor junction formed between cobalt and silicon.
• Cobalt film thickness critically influences the LPV sensitivity, with thinner films showing enhanced positional sensitivity.
• The shorting effect of the metallic film plays a key role in modulating the observed lateral photoeffect.