Enhanced terahertz radiation from InAs (100) with an embedded InGaAs hole blocking layer

Area of Science:

• Solid State Physics
• Optoelectronics
• Terahertz (THz) Science and Technology

Background:

• Terahertz (THz) radiation generation in Indium Arsenide (InAs) is primarily driven by the photo-Dember effect under ultrafast laser excitation.
• Efficient THz emission relies on effective separation of photogenerated electron-hole pairs and the resulting Dember electric field.

Purpose of the Study:

• To enhance THz radiation output from p-type InAs (100) through sophisticated heterostructure engineering.
• To investigate the role of a novel n-InGaAs layer in modulating charge carrier dynamics for improved THz emission.

Main Methods:

• Fabrication of advanced heterostructures incorporating a thin n-InGaAs layer adjacent to the p-InAs (100) surface.
• Characterization of layer structure and doping profiles using secondary ion mass spectrometry (SIMS) and X-ray diffraction (XRD).
• Measurement of surface photovoltage using Kelvin probe force microscopy (KPFM) to verify hole diffusion blocking.

Main Results:

• The inserted n-InGaAs layer effectively impedes hole diffusion while allowing efficient electron transport via tunneling, significantly enhancing photogenerated charge separation.
• This improved charge separation leads to a stronger photo-Dember electric field, resulting in demonstrably enhanced THz radiation intensity.
• Experimental verification confirmed the structural integrity and doping profiles, as well as the successful suppression of hole diffusion.

Conclusions:

• Advanced heterostructure design, specifically the inclusion of a strategically placed n-InGaAs layer, is a viable method for significantly boosting THz emission from InAs.
• The mechanism involves enhanced electron-hole separation by blocking hole diffusion, leading to a stronger photo-Dember effect and increased THz output.
• This approach offers a promising pathway for developing more efficient THz radiation sources.