Magnetic quantum ratchet effect in Si-MOSFETs

Area of Science:

• Solid State Physics
• Quantum Mechanics
• Materials Science

Background:

• Metal-oxide semiconductor field-effect-transistors (MOSFETs) are fundamental semiconductor devices.
• The quantum ratchet effect describes particle motion driven by asymmetric potentials and fluctuating forces.
• Understanding carrier dynamics in MOSFETs under external fields is crucial for device applications.

Purpose of the Study:

• To report the first observation of the magnetic quantum ratchet effect in Si-MOSFETs.
• To investigate the dependence of the induced current on magnetic field strength and AC electric field amplitude.
• To elucidate the underlying physical mechanisms, including quasi-classical and quantum theories.

Main Methods:

• Fabrication and characterization of Si-MOSFETs.
• Excitation of unbiased transistors using terahertz radiation with controlled polarization.
• Application of in-plane magnetic fields.
• Measurement of induced direct current between source and drain contacts.

Main Results:

• Observation of a direct electric current in Si-MOSFETs under terahertz AC electric field and in-plane magnetic field.
• The induced current scales linearly with magnetic field strength and quadratically with AC electric field amplitude.
• The effect is dependent on the polarization of the terahertz radiation and observable with both linear and circular polarization.

Conclusions:

• The magnetic quantum ratchet effect is experimentally demonstrated in Si-MOSFETs.
• The observed current is attributed to the Lorentz force acting on carriers within the asymmetric inversion channels.
• This finding opens new avenues for exploring quantum phenomena and developing novel electronic devices.