Browsing by Author "Lin, Shi-Wei"

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An Anomalous Conductance Decrease in Charge Sensitive Infrared Phototransistor
(2013-01-01)
Kang, Ting-Ting
;
Komiyama, Susumu
;
Ueda, Takeji
;
Lin, Shi-Wei
;
Lin, Sheng-Di
For charge-sensitive infrared phototransistors (CSIP), it is observed that "conductance decrease," which is contrary to the standard "conductance increase" photon response, can also happen after absorbing infrared light. By experimental modeling the charge-up detection mechanism of CSIP via a capacitive way, we clarify that " conductance decrease" should be attributed to the significantly reduced low quantum well electron mobility after the photon-charging process, rather than a reversed electron transfer. This experimental result clearly indicates that photon-induced charges are able to modify the electron mobility in those "charge-sensitive sensor" types of semiconductor quantum single-photon detectors.
Characterization of Single-Crystalline Aluminum Thin Film on (100) GaAs Substrate
(2013-04-01)
Lin, Shi-Wei
;
Wu, Jau-Yang
;
Lin, Sheng-Di
;
Lo, Ming-Cheng
;
Lin, Ming-Huei
We have studied the structure and physical properties of an aluminum thin film grown on a (100) GaAs substrate. The X-ray diffraction (XRD) data shows that the Al film grown in situ by molecular beam epitaxy (MBE) is single crystalline. Compared with the polycrystalline film ex situ evaporated using an electron-gun (E-gun), the MBE-grown Al film has a high optical reflectivity in the visible and ultraviolet (UV) regime. In addition, the MBE-grown film has a 2-order-lower residue resistance, a 1-order-higher temperature coefficient of resistance, and a 2-order-larger magnetoresistance (MR) than the polycrystalline film. Owing to the long mean free time, the bulk-like electron-to-hole transition of Hall resistivity is observed for the first time in a nanoscale metal thin film. Our results suggest that MBE-grown Al thin films have great potential applications in metal-based nanoelectronics and nanophotonics. (C) 2013 The Japan Society of Applied Physics
Single-Crystalline Aluminum Nanostructures on a Semiconducting GaAs Substrate for Ultraviolet to Near-Infrared Plasmonics
(2015-04-01)
Liu, Hsuan-Wei
;
Lin, Fan-Cheng
;
Lin, Shi-Wei
;
Wu, Jau-Yang
;
Chou, Bo-Tsun
Aluminum, as a metallic material for plasmonics, is of great interest because it extends the applications of surface plasmon resonance into the ultraviolet (UV) region and is superior to noble metals in natural abundance, cost, and compatibility with modern semiconductor fabrication processes. Ultrasmooth single-crystalline metallic films are beneficial for the fabrication of high-definition plasmonic nanostructures, especially complex integrated nanocircuits. The absence of surface corrugation and crystal boundaries also guarantees superior optical properties and applications in nanolasers. Here, we present UV to near-infrared plasmonic resonance of single-crystalline aluminum nanoslits and nanoholes. The high-definition nanostructures are fabricated with focused ion-beam milling into an ultrasmooth single-crystalline aluminum film grown on a semiconducting GaAs substrate with a molecular beam epitaxy method. The single-crystalline aluminum film shows improved reflectivity and reduced two-photon photoluminescence (TPPL) due to the ultrasmooth surface. Both linear scattering and nonlinear TPPL are studied in detail. The nanoslit arrays show clear Fano-like resonance, and the nanoholes are found to support both photonic modes and localized surface plasmon resonance. We also found that TPPL generation is more efficient when the excitation polarization is parallel rather than perpendicular to the edge of the aluminum film. Such a counterintuitive phenomenon is attributed to the high refractive index of the GaAs substrate. We show that the polarization of TPPL from aluminum preserves the excitation polarization and is independent of the crystal orientation of the film or substrate. Our study gains insight into the optical property of aluminum nanostructures on a high-index semiconducting GaAs substrate and illustrates a practical route to implement plasmonic devices onto semiconductors for future hybrid nanodevices.