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Fayetteville, AR, United States

Pham T.,University of Arkansas | Du W.,University of Arkansas | Margetis J.,3440 East University Dr | Ghetmiri S.A.,University of Arkansas | And 7 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

Si based Ge1-xSnx photoconductors, with Sn incorporation of 0.9, 3.2, and 7%, were fabricated using a CMOS-compatible process. Temperature dependent study was conducted from 300 to 77 K. The first generation device (standard photoconductor, PD) shows long wavelength cut-off beyond 2.1 μm for 7%-Sn devices at room temperature. The peak responsivity and D∗ of the 7% Sn device at 1.55 μm were obtained at 77K as 0.08 A/W and 1×109 cm∗Hz1/2∗W-1, respectively. Improved responsivity and specific detectivity (D∗) were observed on second generation devices by a newly designed electrode structure (photoconductor with interdigitated electrodes, IEPD). The enhancement factor of responsivity was up to 15 at 77 K. © 2015 SPIE. Source


Pham T.,University of Arkansas | Du W.,University of Arkansas | Tran H.,University of Arkansas | Margetis J.,ASM | And 6 more authors.
Optics Express | Year: 2016

Normal-incidence Ge1-xSnx photodiode detectors with Sn compositions of 7 and 10% have been demonstrated. Such detectors were based on Ge/Ge1-xSnx/Ge double heterostructures grown directly on a Si substrate via a chemical vapor deposition system. A temperaturedependence study of these detectors was conducted using both electrical and optical characterizations from 300 to 77 K. Spectral response up to 2.6 μm was achieved for a 10% Sn device at room temperature. The peak responsivity and specific detectivity (D∗) were measured to be 0.3 A/W and 4 × 109 cmHz1/2W-1 at 1.55 μm, respectively. The spectral D∗ of a 7% Sn device at 77 K was only one order-of-magnitude lower than that of an extended-InGaAs photodiode operating in the same wavelength range, indicating the promising future of GeSn-based photodetectors. © 2016 Optical Society of America. Source


Conley B.R.,University of Arkansas | Margetis J.,3440 East University Drive | Du W.,University of Arkansas | Tran H.,University of Arkansas | And 8 more authors.
Applied Physics Letters | Year: 2014

Thin-film Ge0.9Sn0.1 structures were grown by reduced-pressure chemical vapor deposition and were fabricated into photoconductors on Si substrates using a CMOS-compatible process. The temperature-dependent responsivity and specific detectivity (D∗) were measured from 300 K down to 77 K. The peak responsivity of 1.63 A/W measured at 1.55 μm and 77 K indicates an enhanced responsivity due to photoconductive gain. The measured spectral response of these devices extends to 2.4 μm at 300 K, and to 2.2 μm at 77 K. From analysis of the carrier drift and photoconductive gain measurements, we have estimated the carrier lifetime of this Ge0.9Sn0.1 thin film. The longest measured effective carrier lifetime of 1.0 × 10-6 s was observed at 77 K. © 2014 AIP Publishing LLC. Source


Ghetmiri S.A.,University of Arkansas | Du W.,University of Arkansas | Margetis J.,3440 East University Drive | Mosleh A.,University of Arkansas | And 10 more authors.
Applied Physics Letters | Year: 2014

Material and optical characterizations have been conducted for epitaxially grown Ge1-xSnx thin films on Si with Sn composition up to 10%. A direct bandgap Ge0.9Sn0.1 alloy has been identified by temperature-dependent photoluminescence (PL) study based on the single peak spectrum and the narrow line-width. Room temperature PL emission as long as 2230 nm has also been observed from the same sample. © 2014 AIP Publishing LLC. Source


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase I | Award Amount: 150.00K | Year: 2015

ABSTRACT: Silicon-based lasers/detectors have long been desired for owing to the possibility of monolithic integration of photonics with high-speed Si electronics and the aspiration of broadening the reach of Si technology by expanding its functionalities well beyond electronics. The goal of this project is to first develop high quality SiGeSn material and then use it to demonstrate prototype optoelectronic devices. The research plan includes UHV-CVD growth of mid-IR SiGeSn materials and material characterization as well as development of GeSn mid-IR detectors and lasers. The innovative claims include: i) using novel techniques such as Plasma Enhancement and Atomic Hydrogen Enhancement for device quality SiGeSn growth, ii) high performance GeSn based photodetectors with high responsivity, high gain-bandwidth product, low dark current, CMOS compatibility, and extended spectra response, iii) GeSn based lasers transforming the new active direct band gap material to the first all group-IV inter-band lasers on Si. The work will create significant impacts to the scientific community by enabling the so-called Si optoelectronics superchip, to extend the current Si-photonics wavelength range to mid-infrared, and to enable numerous commercial applications in telecom, consuming electronics, to renewable energy. BENEFIT: Devices such as lasers, detectors, and solar cells with applications in telecom, consuming electronics, and renewable energy

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