Fabrication and Analysis of Epitaxially Grown Ge $_{1-x}$ Sn $_x$ Microdisk Resonator With 20-nm Free-Spectral Range
TL;DR: In this article, a whispering gallery mode (WGM) microdisk resonator based on Ge1-xSnx grown by molecular beam epitaxy (MBE) was fabricated and characterized.
Abstract: In this work, a whispering gallery mode (WGM) microdisk resonator based on Ge1-xSnx grown by molecular beam epitaxy (MBE) was fabricated and characterized. Various process conditions and different Sn contents (4% and 1%) were explored to confirm the feasibility of Ge1-xSnx for microcavity device operation. Optical modes with wavelengths in the infrared (IR) range beyond 1550 nm were successfully confined in the devices fabricated with different diameters, and free-spectral ranges (FSRs) near 20 nm were obtained.
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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
TL;DR: The concept of direct band gap group IV materials offers a paradigm change for Si-photonics concerning the monolithic implementation of light emitters: the idea is to integrate fully compatible group IV material with equally favorable optical properties as the chemically incompatible group III-V-based systems.
Abstract: The concept of direct band gap group IV materials offers a paradigm change for Si-photonics concerning the monolithic implementation of light emitters: The idea is to integrate fully compatible group IV materials with equally favorable optical properties as the chemically incompatible group III-V-based systems The concept involves either mechanically applied strain on Ge or alloying of Ge with Sn and permits to drastically improve the insufficient radiative efficiency of Ge The favorable optical properties result from a modified band structure transformed from an indirect to a direct one The first demonstration of such a direct band gap laser, accomplished in GeSn, exemplifies the capability of this new concept These systems may permit a qualitative as well as a quantitative expansion of Si-photonics into traditional but also new areas of applications, provided they can be operated energy efficiently, under ambient conditions and integrated with current Si technologies This review aims to discuss the challenges along this path in terms of fabrication, characterization and fundamental understanding, and will elaborate on evoking opportunities of this new class of group IV-based laser materials
104 citations
TL;DR: A pseudomorphic Ge/Ge0.92Sn0.08/Ge quantum-well microdisk resonator on Ge/Si (001) as a route toward a compact GeSn-based laser on silicon is theoretically studied and experimentally demonstrated.
Abstract: We theoretically study and experimentally demonstrate a pseudomorphic Ge/Ge0.92Sn0.08/Ge quantum-well microdisk resonator on Ge/Si (001) as a route toward a compact GeSn-based laser on silicon. The structure theoretically exhibits many electronic and optical advantages in laser design, and microdisk resonators using these structures can be precisely fabricated away from highly defective regions in the Ge buffer using a novel etch-stop process. Photoluminescence measurements on 2.7 μm diameter microdisks reveal sharp whispering-gallery-mode resonances (Q > 340) with strong luminescence.
103 citations
TL;DR: In this paper, the authors show that optical germanium-on-insulator (GeOI) substrates fabricated by the Smart Cut™ technology is a key feature for future Si-complementary metal oxide Semiconductor (CMOS) compatible laser demonstration.
60 citations
TL;DR: Electroluminescence peaks were observed near 1550 nm and the energy around this wavelength corresponds to that emitted from direct recombination at the Γ-valley of germanium.
Abstract: Group-IV materials for monolithic integration with silicon optoelectronic systems are being extensively studied. As a part of efforts, light emission from germanium has been pursued with the objective of evolving germanium into an efficient light source for optical communication systems. In this study, we demonstrate room-temperature electroluminescence from germanium in an Al0.3Ga0.7As/Ge heterojunction light-emitting diode without any complicated manipulation for alternating material properties of germanium. Electroluminescence peaks were observed near 1550 nm and the energy around this wavelength corresponds to that emitted from direct recombination at the Γ-valley of germanium.
12 citations
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TL;DR: In this paper, the fabrication of III-V metaloxide-semiconductor (MOS) devices on Ge∕Si virtual substrates using molecular-beam epitaxy was described.
Abstract: We describe the fabrication of III–V metal-oxide-semiconductor (MOS) devices on Ge∕Si virtual substrates using molecular-beam epitaxy. Migration-enhanced epitaxy and low temperature normal GaAs growth produced a sufficiently smooth surface to deposit gate oxides. A 300nm thick GaAs buffer layer was grown, followed by a 10nm growth of In0.2Ga0.8As high mobility channel layer. An 8.5nm thick Al2O3 layer was deposited ex situ by atomic-layer deposition. Capacitance-voltage (C-V) characteristics show the unpinning of Fermi level. This work suggests this materials combination as a promising candidate for the design of advanced, nonclassical complementary MOS and optoelectronic devices on Si substrates.
21 citations
13 Apr 1999
TL;DR: In this article, a high-Q Whispering Gallery Travelling Wave WGTW resonator has been proposed, which can be used as a ring cavity at optical frequencies without degrading the frequency discrimination.
Abstract: Usually a frequency stabilised standing wave resonator-oscillator that incorporates a resonator as a frequency discriminator, requires a circulator to separate the input and reflected wave. A ferrite circulator is a noisy device and can limit the phase noise or frequency stability. Moreover, we show that the noise in a circulator varies, and detailed low noise measurements are necessary to choose an appropriate quite circulator. Thus, by realising a configuration that does not require a circulator an improvement in performance and reliability can be obtained. A solution to this problem is to design a high-Q Whispering Gallery Travelling Wave WGTW resonator. This device naturally separates the input and reflected wave in the same way as a ring cavity at optical frequencies without degrading the frequency discrimination. Q-factor measurements of a WGTW sapphire resonator are presented, along with a derivation of critical parameters to maximise the frequency discrimination. Measurements of noise in ferrite circulators and isolators have also been made which we follow with a discussion on oscillator design.
8 citations
"Fabrication and Analysis of Epitaxi..." refers background in this paper
...…widely used for conventional dielectric resonators in advanced radio frequency (RF) circuits, optical communication systems, and biosensing devices because of their simple device structure, high quality factor, and the possibility of both transverse electric (TE) and transverse magnetic (TM) mode…...
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