Investigation of the terahertz radiation mechanism in gallium arsenide on Si substrate

College

College of Science

Department/Unit

Physics

Document Type

Article

Source Title

NRCP Research Journal

Volume

15

Issue

1

First Page

1

Last Page

7

Publication Date

2016

Abstract

Terahertz (THz) radiation was observed in the reflection geometry from femtosecond laser-excited SI GaAs films deposited on Si substrates (SI-GaAs/Si). The THz spectra were compared to those of bare semi- insulating (SI) GaAs and InAs samples with doping type. The results show that the SI-GaAs/Si film exhibited the strongest emission compared to the other GaAs-based samples and comparable to bulk p-InAs which is the currently-accepted strongest THz semiconductor surface emitter. Optical excitation power dependence experiments showed that the SI-GaAs/Si film saturates slower than p-InAs due to the laser’s deeper penetration depth in GaAs as compared to that of InAs. The type of doping significantly affects the THz emission properties of the semiconductor film. This enhancement in THz radiation in GaAs/Si could be attributed to surge currents by the acceleration of photo-generated carriers in the surface and interface electric fields.

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Disciplines

Physics

Keywords

Submillimeter waves; Gallium arsenide; Silicon; Time-resolved spectroscopy; Molecular beam epitaxy

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