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M. Schmid

Bio: M. Schmid is an academic researcher from University of Stuttgart. The author has contributed to research in topics: Molecular beam epitaxy & Photodetector. The author has an hindex of 13, co-authored 26 publications receiving 874 citations.

Papers
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Journal ArticleDOI
TL;DR: GeSn heterojunction photodetectors on Si substrates were grown with Sn concentration up to 4, fabricated for vertical light incidence, and characterized in this paper, where the complete layer structure was grown by means of ultra low temperature (100 °C) molecular beam epitaxy.
Abstract: GeSn heterojunction photodetectors on Si substrates were grown with Sn concentration up to 4%, fabricated for vertical light incidence, and characterized. The complete layer structure was grown by means of ultra low temperature (100 °C) molecular beam epitaxy. The Sn content shifts the responsivity into the infrared, about 310 nm for the 4% Sn sample. An increase of the optical responsivity for wavelengths higher than 1550 nm can be observed with increasing Sn content. At 1600 nm, the optical responsivity is increased by more than a factor of 10 for the GeSn diode with 4% Sn in comparison to the Ge reference diode.

173 citations

Journal ArticleDOI
TL;DR: GeSn heterojunction p-i-n diodes with a Sn content of 0.5% are grown with a very low temperature growth step in order to suppress Sn surface segregation.
Abstract: GeSn heterojunction p-i-n diodes with a Sn content of 0.5% are grown with a special low temperature molecular beam epitaxy. The Sn incorporation in Ge is facilitated by a very low temperature growth step in order to suppress Sn surface segregation. Diodes with sharp doping transitions are realized as double mesa structures with a diameter from 1.5 up to 80 μm. An optical responsivity of these GeSn diodes of 0.1 A/W at a wavelength of λ=1.55 μm is measured. In comparison with a pure Ge detector the optical responsivity is increased by factor of 3 as a result of Sn caused band gap reduction.

171 citations

Journal ArticleDOI
TL;DR: In this article, an ultra-low temperature molecular beam epitaxy process was used to construct metastable GeSn layers on Si substrates with Sn contents up to 20% and 25%, respectively.

99 citations

Journal ArticleDOI
TL;DR: In this article, a GeSn light-emitting pin diode integrated on Si via a Ge buffer is demonstrated and it is compared with a lightemitting Pin diode made from pure, unstrained Ge on Si.
Abstract: In this letter, a GeSn light-emitting pin diode integrated on Si via a Ge buffer is demonstrated and it is compared with a light-emitting pin diode made from pure, unstrained Ge on Si. The diode layer structures are grown with a special low-temperature molecular beam epitaxy process. The pseudomorphic GeSn layers (1.1% Sn content) on the Ge buffer are compressively strained. Both light-emitting pin diodes clearly show direct bandgap electroluminescence emission at room temperature. The electroluminescence peak of the GeSn light-emitting pin diode is shifted by 20 meV into the infrared region compared to the electroluminescence peak of the unstrained Ge light-emitting pin diode. The shift is due to the lower bandgap of GeSn and the influence of strain.

92 citations

Journal ArticleDOI
TL;DR: All detectors had bandwidth above 40 GHz at enough reverse voltage which increased from zero to -5 V within the given Sn range and caused the depletion of the nominal intrinsic absorber at increasing reverse voltages.
Abstract: GeSn (Sn content up to 4.2%) photodiodes with vertical pin structures were grown on thin Ge virtual substrates on Si by a low temperature (160 °C) molecular beam epitaxy. Vertical detectors were fabricated by a double mesa process with mesa radii between 5 µm and 80 µm. The nominal intrinsic absorber contains carrier densities from below 1·1016 cm−3 to 1·1017 cm−3 for Ge reference detectors and GeSn detectors with 4.2% Sn, respectively. The photodetectors were investigated with electrical and optoelectrical methods from direct current up to high frequencies (40 GHz). For a laser wavelength of 1550 nm an increasing of the optical responsivities (84 mA/W −218 mA/W) for vertical incidence detectors with thin (300 nm) absorbers as function of the Sn content were found. Most important from an application perspective all detectors had bandwidth above 40 GHz at enough reverse voltage which increased from zero to −5 V within the given Sn range. Increasing carrier densities (up to 1·1017 cm−3) with Sn contents caused the depletion of the nominal intrinsic absorber at increasing reverse voltages.

91 citations


Cited by
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Journal ArticleDOI
TL;DR: Zhou et al. as discussed by the authors assess the three main contenders for on-chip light sources: erbium-based light sources, germanium-on-silicon lasers and III-V-based silicon lasers.
Abstract: Hybrid silicon lasers based on bonded III–V layers on silicon are currently the best contenders for on-chip lasers for silicon photonics. On-chip silicon light sources are highly desired for use as electrical-to-optical converters in silicon-based photonics. Zhiping Zhou and Bing Yin of Peking University in China and Jurgen Michel of Massachusetts Institute of Technology assess the three main contenders for such light sources: erbium-based light sources, germanium-on-silicon lasers and III-V-based silicon lasers. They consider operating wavelength, pumping conditions, power consumption, thermal stability and fabrication process. The scientists regard the power efficiencies of electrically pumped erbium-based lasers as being too low and the threshold currents of germanium lasers as being too high. They conclude that III–V quantum dot lasers monolithically grown on silicon show the most promise for realizing on-chip lasers.

448 citations

Journal ArticleDOI
TL;DR: A comprehensive summary of the recent progress mainly on photodetectors based on inorganic p-type semiconductor materials is presented.
Abstract: Photoelectric detectors are the central part of modern photodetection systems with numerous commercial and scientific applications. p-Type semiconductor materials play important roles in optoelectronic devices. Photodetectors based on p-type semiconductor materials have attracted a great deal of attention in recent years because of their unique properties. Here, a comprehensive summary of the recent progress mainly on photodetectors based on inorganic p-type semiconductor materials is presented. Various structures, including photoconductors, phototransistors, homojunctions, heterojunctions, p-i-n junctions, and metal-semiconductor junctions of photodetectors based on inorganic p-type semiconductor materials, are discussed and summarized. Perspectives and an outlook, highlighting the promising future directions of this research field, are also given.

290 citations

Journal ArticleDOI
TL;DR: In this paper, the transition from an indirect to a fundamental direct bandgap material will be discussed, and the most commonly used approaches, i.e., molecular beam epitaxy (MBE) and chemical vapor deposition (CVD), will be reviewed in terms of crucial process parameters, structural as well as optical quality and employed precursor combinations including Germanium hydrides, Silicon hydride and a variety of Sn compounds like SnD4, SnCl4 or C6H5SnD3.

193 citations

Journal ArticleDOI
TL;DR: In this paper, an atmospheric pressure-chemical vapor deposition technique was proposed to grow metastable GeSn epitaxial layers on Ge substrates with Sn contents up to 8% and those metastable layers stay fully strained after 30min anneal in N2 at 500°C; Ge-Sn interdiffusion is seen at 500 °C but not at lower temperature.
Abstract: In this letter, we propose an atmospheric pressure-chemical vapor deposition technique to grow metastable GeSn epitaxial layers on Ge. We report the growth of defect free fully strained undoped and in-situ B doped GeSn layers on Ge substrates with Sn contents up to 8%. Those metastable layers stay fully strained after 30 min anneal in N2 at 500 °C; Ge-Sn interdiffusion is seen at 500 °C but not at lower temperature. B is 100% active in the in-situ GeSn:B layers up to a concentration of 1.7 × 1019 cm−3. GeSn:B provides slightly lower Hall hole mobility values than in pure p-type Ge especially for low B concentrations.

182 citations

Journal ArticleDOI
TL;DR: In this paper, a temperature-dependent photoluminescence (PL) study based on the single peak spectrum and the narrow line width was conducted for epitaxially grown Ge1−xSnx thin films on Si with Sn composition up to 10%.
Abstract: 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.

178 citations