Photon Drag Currents and Terahertz Generation in α-Sn/Ge Quantum Wells

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Quantum well heterostructures are crucial for advanced electronic and photonic devices.
• Tin (Sn) and Germanium (Ge) are key materials in semiconductor research.
• Topological electronic states offer novel properties for future technologies.

Purpose of the Study:

• To fabricate and characterize alpha-Sn/Ge quantum well heterostructures.
• To investigate the electronic properties and topological nature of the interfaces.
• To explore the terahertz (THz) radiation generation capabilities of these novel structures.

Main Methods:

• E-beam deposition for sample fabrication.
• Raman spectroscopy and atomic force microscopy for structural characterization.
• Temperature-dependent electrical resistivity and THz time-resolved spectroscopy for electronic property analysis.

Main Results:

• Successful fabrication of alpha-Sn/Ge quantum wells with high electron mobility (2500 cm²/Vs).
• Observation of topologically non-trivial electronic states at the alpha-Sn/Ge interface, indicated by unique resistivity behavior.
• Discovery of unusual, strong THz radiation generation and photocurrent, attributed to photon drag current in topologically protected channels.

Conclusions:

• The fabricated alpha-Sn/Ge quantum wells host topologically protected electronic states with high electron mobility.
• These heterostructures exhibit significantly enhanced THz radiation generation compared to Ge, driven by novel photocurrent mechanisms.
• The findings open new avenues for THz optoelectronics and topological quantum devices.