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Faustino MAB, Lopez LP, Pauline Afalla J, Muldera J, Hermosa N, Salvador AA, Somintac AS, Estacio ES. Terahertz emission enhancement in semi-insulating gallium arsenide integrated with subwavelength one-dimensional metal line array. Opt Lett 2016; 41:4515-4517. [PMID: 27749869 DOI: 10.1364/ol.41.004515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A one-order-of-magnitude terahertz (THz) emission enhancement in the transmission geometry, over a 0.7-THz broadband range, was observed in semi-insulating gallium arsenide (SI-GaAs) integrated with a subwavelength one-dimensional metal line array (1DMLA). THz emission of the 1DMLA samples showed an intensity increase and exhibited a full-width-at-half-maximum broadening relative to the emission of the bare substrate. Improved index matching could not account for the observed phenomenon. A nonlinear dependence of the integrated THz emission intensity on the number of illuminated lines and on the pump power was observed. The actual origin of the increased THz emission is still under investigation. At present, it is attributed to extraordinary optical transmission.
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delos Santos R, Ibañes JJ, Balgos MH, Jaculbia R, Afalla JP, Bailon-Somintac M, Estacio E, Salvador A, Somintac A, Que C, Tsuzuki S, Yamamoto K, Tani M. Dynamics of Optically-Generated Carriers in Si (100) and Si (111) Substrate-Grown GaAs/AlGaAs Core-Shell Nanowires. Nanoscale Res Lett 2015; 10:1050. [PMID: 26293496 PMCID: PMC4545763 DOI: 10.1186/s11671-015-1050-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 08/15/2015] [Indexed: 06/04/2023]
Abstract
GaAs/Al0.1Ga0.9As core-shell nanowires (CSNWs), with average lateral size of 125 nm, were grown on gold nanoparticle-activated Si (100) and Si (111) substrates via molecular beam epitaxy. Room temperature-photoluminescence (RT-PL) from the samples showed bulk-like GaAs and Al0.1Ga0.9As bandgap emission peaks at 1.43 and 1.56 eV, respectively. Higher PL emission intensity of the sample on Si (111) compared to that on Si (100) is attributed to uniform Al0.1Ga0.9As shell passivation of surface states on Si (111)-grown CSNWs. Carrier dynamics in two different temporal regimes were studied. In the sub-nanosecond time scale (300-500 ps), time-resolved radiative recombination efficiency of carriers was examined. In the 0-4 ps range, surface field-driven ballistic transport of carriers was probed in terms of the radiated terahertz (THz) waves. Time-resolved PL measurements at 300 K revealed that the carrier recombination lifetime of the GaAs core on Si (100)-grown CSNWs is 333 ps while that on Si (111)-grown sample is 500 ps. Ultrafast photoexcitation of GaAs core on the two samples generated a negligible difference in the intensity and bandwidth of emitted THz radiation. This result is ascribed to the fact that the deposited GaAs material on both substrates produced samples with comparable NW densities and similar GaAs core average diameter of about 75 nm. The samples' difference in GaAs core's carrier recombination lifetime did not influence THz emission since the two processes involve distinct mechanisms. The THz spectrum of CSNWs grown on Si (111) exhibited Fabry-Perot modes that originated from multiple reflections of THz waves within the Si substrate.
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Affiliation(s)
- Ramon delos Santos
- />National Institute of Physics, University of the Philippines, Diliman, Quezon City, Philippines
- />Department of Physics, Ateneo de Manila University, Quezon City, Philippines
| | - Jasher John Ibañes
- />National Institute of Physics, University of the Philippines, Diliman, Quezon City, Philippines
| | - Maria Herminia Balgos
- />National Institute of Physics, University of the Philippines, Diliman, Quezon City, Philippines
| | - Rafael Jaculbia
- />National Institute of Physics, University of the Philippines, Diliman, Quezon City, Philippines
| | - Jessica Pauline Afalla
- />National Institute of Physics, University of the Philippines, Diliman, Quezon City, Philippines
| | - Michelle Bailon-Somintac
- />National Institute of Physics, University of the Philippines, Diliman, Quezon City, Philippines
| | - Elmer Estacio
- />National Institute of Physics, University of the Philippines, Diliman, Quezon City, Philippines
| | - Arnel Salvador
- />National Institute of Physics, University of the Philippines, Diliman, Quezon City, Philippines
| | - Armando Somintac
- />National Institute of Physics, University of the Philippines, Diliman, Quezon City, Philippines
| | - Christopher Que
- />Department of Physics, De La Salle University, Manila, Philippines
| | - Satoshi Tsuzuki
- />Research Center for Development of Far-Infrared Region, University of Fukui, Fukui, Japan
| | - Kohji Yamamoto
- />Research Center for Development of Far-Infrared Region, University of Fukui, Fukui, Japan
| | - Masahiko Tani
- />Research Center for Development of Far-Infrared Region, University of Fukui, Fukui, Japan
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