Semiconductor Characterization by Terahertz Excitation Spectroscopy

Area of Science:

• Condensed Matter Physics
• Materials Science
• Optoelectronics

Background:

• Semiconducting materials emit terahertz (THz) radiation when excited by femtosecond laser pulses.
• Ultrafast photocurrents and hot-carrier effects govern THz emission, requiring advanced experimental techniques for study.

Purpose of the Study:

• To review a decade of investigations using THz excitation spectroscopy (TES).
• To highlight TES as a contactless method for studying semiconductor band structure and ultrafast processes.

Main Methods:

• Utilizing femtosecond laser pulses and optical parametric amplifiers for tunable excitation.
• Employing THz excitation spectroscopy (TES) to probe carrier dynamics in semiconductors.

Main Results:

• TES experiments reviewed cover bulk semiconductors (GaAs, InAs, InSb, Ge, Te, GaSe) and low-dimensional materials (Bi films, InAs, InGaAs, GaAs nanowires).
• The technique reveals ultrafast processes at different electron energy levels.

Conclusions:

• THz excitation spectroscopy is a versatile, non-contact tool for investigating ultrafast carrier dynamics in diverse semiconductor materials.
• This method provides insights into the electronic properties of both bulk and nanostructured semiconductors.