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

• Main Authors: Muldera, Joselito E., Balgos, Ma. Herminia, Lopez, Lorenzo, Jr., Prieto, Elizabeth Anne, Tumangil, Mae Agatha, Gonzales, Karl Cedric, Simon, Rhenish C., Catindig, Gerald, Sadia, Cyril P., Somintac, Armando S., Salvador, Arnel A., Estacio, Elmer S.
• Format: text
• Published: Animo Repository 2016
• Subjects: Submillimeter waves; Gallium arsenide; Silicon; Time-resolved spectroscopy; Molecular beam epitaxy; Physics
• Online Access: https://animorepository.dlsu.edu.ph/faculty_research/11584
• Institution: De La Salle University

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.