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Opt Express. 2015 Jun 01;23(11):14532-40. doi: 10.1364/OE.23.014532.

Confined photocarrier transport in InAs pyramidal quantum dots via terahertz time-domain spectroscopy.

Optics express

Jorge Michael M Presto, Elizabeth Ann P Prieto, Karim M Omambac, Jessica Pauline C Afalla, Deborah Anne O Lumantas, Arnel A Salvador, Armando S Somintac, Elmer S Estacio, Kohji Yamamoto, Masahiko Tani

PMID: 26072813 DOI: 10.1364/OE.23.014532

Abstract

We present experimental demonstration of photocarrier dynamics in InAs quantum dots (QDs) via terahertz (THz) time-domain spectroscopy (TDS) using two excitation wavelengths and observing the magnetic field polarity characteristics of the THz signal. The InAs QDs was grown using standard Stranski-Krastanow technique on semi-insulating GaAs substrate. Excitation pump at 800 nm- and 910 nm-wavelength were used to distinguish THz emission from the InAs/GaAs matrix and InAs respectively. THz-TDS at 800 nm pump revealed intense THz emission comparable to a bulk p-InAs. For 910 nm pump, the THz emission generally weakened and upon applying external magnetic field of opposite polarities, the THz time-domain plot exhibited anomalous phase-shifting. This was attributed to the possible current-surge associated with the permanent dipole in the QD.

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