Scalable quantum photonic technologies require deterministic sources of entangled photons that are compatible with established semiconductor manufacturing platforms. While self-assembled III–V semiconductor quantum dots are among the most promising sources of on-demand entanglement generation, their integration with silicon-based architectures remains a central challenge. Here, we demonstrate energy–time entanglement from a single InGaAs/GaAs quantum dot monolithically grown on a silicon substrate. Under coherent two-photon excitation, we achieve coherent control of the biexciton–exciton cascade, evidenced by Rabi oscillations and dressed-state formation. Using a four-channel Franson interferometer, we observe phase-dependent two-photon interference with visibilities up to (64.0 ± 7.0)% for an 80 ps integration window (and (49.4 ± 1.9)% for a 1600 ps window), approaching the threshold for Bell inequality violation at short time scales. These results establish monolithically integrated III–V-on-silicon quantum dots as promising sources of energy–time entangled photons for scalable quantum photonic technologies.

We demonstrate for the first time on-chip monolithic integration of quantum-dot (QD) lasers coupled to foundry-processed SiN waveguides on 300 mm SOI wafer with direct in-pocket MBE growth and etched-facet mirrors. This enables scalable prodcution of next-generation on-chip light sources for Si photonics.

Optical interconnect data rates are rapidly increasing, which is driving the intimate 3D integration of photonics and electronics. As a key step in this development, we report the direct growth of quantum dot (QD) lasers with electrical pumping on 300 mm Si wafers on both a planar template and in-pocket template for in-plane photonic integration. O-band lasers with five QD layers were grown with molecular beam epitaxy (MBE) in a 300 mm reactor and then fabricated into standard Fabry-Perot ridge waveguide cavities. Edge-emitting lasers are demonstrated with high yield and reliable results ready for commercialization and scaled production, and efforts to make monolithically integrated lasing cavities grown on silicon-on-insulator (SOI) wafers vertically aligned and coupled to SiN waveguides on the same chip show the potential for 300 mm-scale Si photonic integration with in-pocket direct MBE growth.

Integrating quantum dot (QD) gain elements onto Si photonic platforms via direct epitaxial growth is the ultimate solution for realizing on‐chip light sources. Tremendous improvements in device performance and reliability have been demonstrated in devices grown on planar Si substrates in the last few years. Recently, electrically pumped QD lasers deposited in narrow oxide pockets in a butt‐coupled configuration and on‐chip coupling have been realized on patterned Si photonic wafers. However, the device yield and reliability, which ultimately determines the scalability of such technology, are limited by material uniformity. Here, detailed analysis is performed, both experimentally and theoretically, on the material asymmetry induced by the pocket geometry and provides unambiguous evidence suggesting that all pockets should be aligned to the [1 1¯0$\bar{1}\ 0$ ] direction of the III‐V crystal for high yield, high performance, and scalable on‐chip light sources at 300 mm scale.

We report for the first time the direct growth of quantum dot (QD) lasers with electrical pumping on 300 mm Si wafers on both a planar template and in-pocket template for in-plane photonic integration. O-band lasers with five QD layers were grown with molecular beam epitaxy (MBE) in a 300 mm reactor and then fabricated into standard Fabry–Perot ridge waveguide cavities. Edge-emitting lasers are demonstrated with high yield and reliable results ready for commercialization and scaled production, and efforts to make monolithically integrated lasing cavities grown on silicon-on-insulator (SOI) wafers vertically aligned and coupled to SiN waveguides on the same chip show the potential for 300 mm-scale Si photonic integration with in-pocket direct MBE growth.

We report the first electrically pumped InAs quantum-dot lasers grown on Si within narrow oxide pockets for monolithic on-chip light sources. High performance devices are achieved at 300 mm wafer scale with high yields.

We report the first electrically pumped InAs quantum dot lasers grown in narrow oxide pockets patterned on 300 mm Si wafer for monolithic on-chip light source. This architecture should enable the next generation of photonics integrated circuit platforms.

Monolithic integration of quantum dot (QD) gain materials onto Si photonic platforms via direct epitaxial growth is a promising solution for on-chip light sources. Recent developments have demonstrated superior device reliability in blanket hetero-epitaxy of III–V devices on Si at elevated temperatures. Yet, thick, defect management epi designs prevent vertical light coupling from the gain region to the Si-on-Insulator waveguides. Here, we demonstrate the first electrically pumped QD lasers grown by molecular beam epitaxy on a 300 mm patterned (001) Si wafer with a butt-coupled configuration. Unique growth and fabrication challenges imposed by the template architecture have been resolved, contributing to continuous wave lasing to 60 °C and a maximum double-side output power of 126.6 mW at 20 °C with a double-side wall-plug efficiency of 8.6%. The potential for robust on-chip laser operation and efficient low-loss light coupling to Si photonic circuits makes this heteroepitaxial integration platform on Si promising for scalable and low-cost mass production.

Critical point transition energies and optical functions of the novel GaAs-based dilute bismide alloys GaAsBi, GaNAsBi, and GaPAsBi were determined using spectroscopic ellipsometry. The ellipsometry data were analyzed using a parameterized semiconductor model to represent the dielectric function of the alloys as the sum of Gaussian oscillators centered on critical points in the band structure, and from this extracting the energies of those critical points. The band gap and spin-orbit splitting were measured for samples for a range of alloy compositions. The first experimental measurements of the spin-orbit splitting in the GaNAsBi quaternary alloy were obtained, which showed that it is approximately independent of N content, in agreement with theory. The real component of the refractive index in the transparent region below the band gap was found to decrease as the band gap increased for all of the alloys studied, following the usual relations for conventional semiconductors. This work provides key electronic and optical parameters for the development of photonic devices based on these novel alloys.

The maturity of GaAs/AlAs-based technology enabled the fabrication of highly efficient diode lasers based on (AlGaIn)As/GaAs as well as (AlGa)As/GaAs active regions. Furthermore, these material systems have proven to be widely adaptable, because the GaAs/AlAs system allows for the fabrication of various cavity concepts including in-plane as well as vertically emitting laser structures and the emission wavelengths of the above-mentioned active regions can be tailored from the red to the near-infrared wavelength regime. However, the fabrication of GaAs-based telecommunication lasers proved to be difficult due to the high quality requirements in combination with strain-induced defect formation. While the demonstration of 1.3 μm lasers based on Ga(AsSb)/GaAs [1] as well as (GaIn)(NAs)/GaAs [2] was possible, (GaIn)(AsP)/InP and (AlGaIn)As/InP remained the dominant material systems for lasers emitting at wavelengths longer than 1.2 μm.

Bi containing MN semiconductors are frequently mentioned for their importance as part of the next generation of optoelectronic devices. Bi containing ternary and quaternary materials like Ga(AsBi), Ga(NAsBi) or Ga(PAsBi) are promising candidates to meet the requirements for new laser structures for telecommunications and solar cell applications. However, in previous studies it was determined that the incorporation of sufficient amounts of Bi still poses a challenge, especially when using MOVPE (metalorganic vapour phase epitaxy) as the growth technique. In order to figure out which mechanisms are responsible for the limitation of Bi incorporation, this work deals with the question of whether there is a relationship between strain, induced by the large Bi atoms, and the saturation level of Bi incorporation in Ga(AsBi).Ga(NAsBi) structures were grown by MOVPE at a low temperature, 400 degrees C, and compared to Ga(PAsBi) as well as Ga(AsBi) growth. By using the two group V atoms P and N, which have a smaller covalent radius than Bi, the effect of local strain compensation was investigated systematically. The comparison of Bi incorporation in the two quaternary materials systems proved the importance of local strain for the limitation of Bi incorporation, in addition to other effects, like Bi surface coverage and hydrocarbon groups at the growth surface. This, of course, also opens up ways to strain-state-engineer the Bi incorporation in semiconductor alloys. (C) 2017 Elsevier B.V. All rights reserved.

GaNAs/GaP/BGaAsP-multiple quantum well heterostructures (MQWH) were deposited pseudomorphically strained on exactly oriented (001) Si-substrate plus thin GaP buffer by metal organic vapor phase epitaxy (MOVPE). The compressive strain of the GaNAs QW material enabled N fractions as high as 16.8%. Structural analyses show that the structures exhibit high crystalline quality for moderate strain values of 0.6% to 2.2%. Room temperature PL was obtained from samples with up to 11% N with an emission wavelength of up to 1130nm. At low temperatures (15K) even layers with 15% N showed photoluminescence from the GaNAs QW expanding the emission wavelength range to 1300nm.

Peculiarities of the excitation-dependent photoluminescence (PL) lineshape in Ga(NAsP)/GaP multiple quantum well structures are studied both experimentally and theoretically. A peculiar behavior of the PL peak energy and PL full width at half maximum (FWHM) at low temperatures is revealed experimentally. The PL peak energy increases with the increasing excitation intensity and tends to saturation at high excitation intensities, reflecting the gradual filling of the disorder-induced localized states. The PL FWHM initially decreases with the increasing excitation intensity, reaching a minimum at a relatively high excitation intensity, and then increases for higher excitation intensities. Such a non-monotonous behavior of the PL lineshape is explained by the hopping relaxation of excitons in the tail of localized states, assuming a non-monotonous density of localized states, consisting of exponential and Gaussian components.

Dilute bismide containing materials can play an important role in addressing the issue of finding new highly efficient lasers for telecommunications as well as sensing applications. In the last several years a growing body of literature has emerged, particularly on the growth of Ga(AsBi). However, the metal organic vapor phase epitaxy growth of Ga(AsBi) with high amounts of Bi, which are necessary to overcome Auger recombination and reach telecommunications wavelengths, still remains a challenge. Ga(PBi) could be a promising alternative, but has not been deposited with significant amounts of Bi so far. A second argument for Ga(PBi) is that it could be grown on GaP, which was already deposited on Si. A number of researchers have reported theoretical calculations on the band structure of Ga(PBi), but experimental results are still lacking.In this work we present the first Ga(PBi) structures, grown by metal organic vapor phase epitaxy on GaP and on GaP on Si. By careful characterization with high resolution X-ray diffraction, atomic force microscopy, secondary ion mass spectrometry and scanning transmission electron microscopy, we will show that we have realized high quality Ga(PBi) with Bi fractions over 8%. (C) 2017 Elsevier B.V. All rights reserved.

We demonstrate a new class of GaAs-based type II quantum wells based on the highly mis-matched III–V semiconductor alloys GaAs 1-x Bi x and GaNyAs 1-y . We theoretically quantify and analyse the available design space for the growth of GaAs 1-x Bi x /GaN y As 1-y type II structures on GaAs. Our calculations indicate that, for alloy compositions and layer thicknesses comparable with epitaxial growth, these heterostructures offer optical emission and absorption at wavelengths up to 3 µm as well as the ability to grow strain-balanced structures. We present the results of experimental measurements on a GaAs 1-x Bi x /GaNyAs 1-y (x = 3.3%, y = 6.25%) structure, grown via metal-organic vapor phase epitaxy. X-ray diffraction measurements indicate good structural quality, which is confirmed by the observation of photoluminescence and optical absorption at room temperature. The measured photoluminescence peak wavelength of 1.72 µm, which is in good agreement with theoretical calculations is, to our knowledge, the longest emission wavelength that has been observed to date using a pseudomorphically grown GaAs-based quantum confined heterostructure.

We study the magnetotransport properties of n-type BxGa1-x As-0.11 P-0.89: Te alloy samples with 0 <= x <= 0.038 in magnetic fields up to 4 T between 10 and 280 K, some samples also under hydrostatic pressure up to 15 kbar. As a general trend the resistivity increases with increasing x, as both the carrier concentration and the mobility of electrons decrease. The free carrier concentration and mobility of the reference sample GaAs0.11 P-0.89: Te is almost independent of the applied hydrostatic pressure, in particular, at higher temperatures whereas the B0.018Ga0.982As0.11P0.89: Te sample exhibits a different behavior. Its resistivity decreases due to a substantial increase of its free carrier concentration under pressure. This behavior is explained by the existence of a boron-related density of localized states in the vicinity of the conduction band edge of the alloy. The boron states act as electron traps as well as efficient scattering centers. Applying hydrostatic pressure shifts the energetic positions of conduction band edge at the X-point and of the boron states apart, reducing the impact of boron on the electronic transport properties of the alloy.

Time-resolved photoluminescence (TR-PL) measurements have been performed in Ga(NAsP)/(BGa)(AsP) multi-quantum well heterostructures (MQWHs) with different well thicknesses. The studied structures have been pseudomorphically grown on Si substrates by metal organic vapor phase epitaxy (MOVPE) with an N content of about 7%. Experimental results reveal a shortening in the PL decay time with increasing QW thickness, meanwhile, accompanied by a decrease in the PL intensity. We attribute this behavior to an increasing non-radiative recombination rate for broader QWs which arises from an increasing number of defects in the QW material. The emission-energy distribution of the PL decay time is studied at various temperatures. The PL decay time strongly depends on the emission energy at low temperatures and becomes emission-energy-independent close to room temperature. This is discussed in terms of the carrier localization in the studied structures.

In einigen Untersuchungen konnte gezeigt werden, dass CEACAM1 durch hypoxische und entzundliche Vorgange hochreguliert wird und durch Stimulierung von Angiogenese und Kollateralisierung diesen Zustanden entgegenwirkt. Ursachlich fur viele angioproliferative Augenerkrankungen sind Hypoxie und Inflammation, weswegen anzunehmen ist, dass CEACAM1 bei diesen Krankheiten eine Rolle spielt. Ziel dieser Arbeit war es daher, den Einfluss von CEACAM1 auf angioproliferative Augenerkrankungen zu beschreiben. Als Modell fur die angioproliferativen Netzhauterkrankungen wurde die Fruhgeborenenretinopathie in der Maus gewahlt. Bei diesem Krankheitsbild kommt es bei neugeborenen Mausen durch Hyperoxie zunachst zu Gefasuntergang. Aufgrund der nun fehlenden Gefase leiden die Zellen der Netzhaut nach Transfer in Raumluft an relativem Sauerstoffmangel, was zu einer massiven Ausschuttung von proangiogenen Wachstumsfaktoren mit Bildung von Mikroaneurysmen fuhrt. In der letzten Phase der Fruhgeborenenretinopathie werden diese pathologischen Neovaskularisationen abgebaut und die avaskularen, retinalen Bereiche revaskularisiert. In der vorliegenden Arbeit konnte gezeigt werden, dass der Verlust von CEACAM1 zu einem groseren Gefasuntergang wahrend der Hyperoxie mit anschliesenden, vermehrten Neovaskularisationen fuhrt. Die erhohte Empfindlichkeit des Endothels gegenuber Sauerstoff in Ceacam1-/-- Mausen liegt vermutlich an einer gesteigerten Aktivitat des Enzyms eNOS, das durch CEACAM1 negativ reguliert wird und reaktive Sauerstoffspezies produziert, die das Endothel schadigen. Zugleich ist der Abbau der Neovaskularisationen bei den Ceacam1-/-- Mausen verzogert, genauso wie die Revaskularisierung. Moglicherweise werden diese Effekte von CEACAM1 uber Mikroglia vermittelt. Mikroglia schutzen nachweislich vor Gefasuntergang in der Netzhaut und fordern Revaskularisierung. In den Ceacam1-/-- Mausen wiesen mehr Mikroglia eine ruhende, sogenannte ramifizierte Morphologie auf. Zusatzlich war die Expression von Iba1, einem Aktivitatsmarker von Mikroglia, vermindert, sodass CEACAM1 moglicherweise in die Aktivierung von Mikroglia involviert ist. Um die Rolle von CEACAM1 in der Regulation von Mikroglia zu bestatigen, wurden CD11b- positive Zellen, die in der Netzhaut zu Mikroglia differenzieren, aus B6.WT und B6. Ceacam1-/-- Mausen in die Augen von Mausen mit Fruhgeborenenretinopathie injiziert. Die Zellen, denen CEACAM1 fehlte, konnten im Gegensatz zu CEACAM1- positive Zellen nicht in die Netzhaut migrieren und zu Mikroglia differenzieren. Mit groser Wahrscheinlichkeit sind auch andere CEACAM1- exprimierende Zellen an der Pathogenese der Fruhgeborenenretinopathie beteiligt, z.B. Endothelzellen, Perizyten und T- Lymphozyten. Die Tip- Zellen der Endothelzellen zeigten in B6.WT und B6. Ceacam1-/-- Mausen allerdings keine Unterschiede in der Lange. Die Rolle der Perizyten und T- Lymphozyten wurde in dieser Arbeit nicht naher untersucht, sodass nur Hypothesen aufgestellt werden konnten, die noch bestatigt oder widerlegt werden mussen. Zusammenfassend bestatigen die Versuche dieser Arbeit, dass der Verlust von CEACAM1 zwar unter physiologischen Bedingungen keine Auswirkungen auf die Gefasentwicklung hat, hingegen unter Hypoxie und Inflammation viele Prozesse, wie Angiogenese, beeintrachtigt sind. Auserdem lassen einige Ergebnisse vermuten, dass CEACAM1 viele seiner Effekte nicht nur uber endotheliale Zellen sondern auch uber andere Zellpopulationen, wie CD11b- positive Zellen, vermittelt.

We have studied the optical properties of Ga(NAsP)-heterostructures, which were systematically grown at different temperatures by means of continuous-wave and time-resolved photoluminescence. We show that both the long ranged and the short ranged disorder scales increase for higher growth temperatures. Furthermore, samples with a higher disorder not only emit less photoluminescence (PL) intensity but also exhibit a longer effective PL decay time.

Dilute bismide Ga(PAsBi)-based structures are promising candidates for highly efficient optoelectronic applications, like the 1 eV sub-cell in multi-junction solar cells or the active region in infra-red laser diodes. The band gap can be tuned independently from the lattice constant, which theoretically enables the deposition of lattice-matched layers in a wide range of band gap energies on GaAs substrate. In this work, firstly, the shifts in the band edge positions as a function of composition that are possible with the Ga(PAs(Bi)) alloy were estimated using the virtual crystal approximation and valence band anti-crossing theory. Secondly, systematic investigations on MOVPE growth of Ga(PAsBi) layers are presented. Finally, we show the first photoluminescence activity of quaternary Ga(PAsBi) and compare the experimental results to theory. (C) 2016 Elsevier Ltd. All rights reserved.