Spectral dependencies of THz pulse emission from GaSb

Area of Science:

• Solid State Physics
• Materials Science
• Spectroscopy

Background:

• Gallium Antimonide (GaSb) is a crucial semiconductor material with unique electronic properties.
• Understanding carrier dynamics in doped GaSb surfaces is essential for advanced electronic device applications.
• Terahertz (THz) spectroscopy offers a non-contact method to probe ultrafast carrier phenomena.

Purpose of the Study:

• To investigate the THz excitation spectroscopy of doped (100) GaSb surfaces.
• To identify distinct THz generation mechanisms in p-type and n-type GaSb.
• To explore the influence of excitation photon energy and azimuthal angle on THz generation.

Main Methods:

• Utilized THz excitation spectroscopy with photon energies from 0.6 eV to 1.2 eV.
• Generated THz pulses by exciting doped (100) GaSb surfaces.
• Analyzed the azimuthal angle dependence of the generated THz pulse amplitude.

Main Results:

• Identified the photo-Dember effect as the primary THz generation mechanism for p-doped GaSb.
• Identified drift current in the surface field as the primary THz generation mechanism for n-doped GaSb.
• Observed azimuthal angle dependence of THz amplitude due to Γ valley non-parabolicity at low energies (<0.82 eV).
• Observed a polarity shift in azimuthal dependence above 0.82 eV, attributed to carrier scattering into the L valley.

Conclusions:

• Established distinct THz generation pathways for p- and n-doped GaSb surfaces.
• Demonstrated the role of band non-parabolicity and intervalley scattering in THz generation.
• Highlighted the potential of THz spectroscopy for characterizing carrier dynamics in semiconductors.