High-quality Ge epilayers on Si with low threading-dislocation densities were achieved by a two-step ultrahigh vacuum/chemical-vapor-deposition process followed cyclic thermal annealing. On large wafers, density of 2.3×107 cm−2 was obtained. Combining selective area growth annealing produced an average 2.3×106 cm−2.We also demonstrated small mesas no threading dislocations. The described in this letter for making high-quality is uncomplicated and can be easily integrated standard processes.

Band gap shrinkage induced by tensile strain is shown for Ge directly grown on Si substrate. In Ge-on-Si pin diodes, photons having energy lower than the direct band of bulk were efficiently detected. According to photoreflectance measurement, this property due shrinkage. The origin not Franz–Keldysh effect but rather strain. It discussed that generation such a can be ascribed difference thermal expansion between and Si. Advantages application photodiode are also discussed.

Abstract The emergence of silicon photonics over the past two decades has established as a preferred substrate platform for photonic integration. While most silicon-based components have so far been realized in near-infrared (near-IR) telecommunication bands, mid-infrared (mid-IR, 2–20-μm wavelength) band presents significant growth opportunity integrated photonics. In this review, we offer our perspective on burgeoning field mid-IR silicon. A comprehensive survey state-of-the-art key...

Spatially resolved cathodoluminescence (CL) spectrum mapping revealed a strong exciton localization in InGaN single-quantum-wells (SQWs). Transmission electron micrographs exhibited well-organized SQW structure having abrupt InGaN/GaN heterointerfaces. However, comparison between atomic force microscopy images for GaN-capped and uncapped SQWs indicated areas of InN-rich material, which are about 20 nm lateral size. The CL taken at the higher lower energy side spatially integrated peak...

Emission mechanisms of a device-quality quantum well (QW) structure and bulk three dimensional (3D) InGaN materials grown on sapphire substrates without any epitaxial lateral overgrown GaN base layers were investigated. The InxGa1−xN showed various degrees in-plane spatial potential (band gap) inhomogeneity, which is due to compositional fluctuation or few monolayers thickness fluctuation. degree changed remarkably around nominal InN molar fraction x=0.2, changes nearly 0.08–0.1 for the...

We have fabricated Ge/Si heterojunction photodetectors with high responsivities of 550 mA/W at 1.32 μm and 250 1.55 time responses shorter than 850 ps. High quality Ge was epitaxially grown on Si using ultrahigh vacuum/chemical vapor deposition followed by cyclic thermal annealing. The beneficial effect the post-growth annealing electrical properties epilayers, due to reduction threading-dislocation densities, is confirmed dramatic enhancement performance photodetectors.

We demonstrate a high-performance, tensile-strained Ge p-i-n photodetector on Si platform with an extended detection spectrum of 650–1605 nm and 3 dB bandwidth 8.5 GHz measured at λ=1040nm. The full the is achieved low reverse bias 1 V, compatible driving voltage requirements ultralarge-scale integrated circuits. Due to direct bandgap shrinkage induced by 0.20% tensile strain in layer, device covers entire C band large part L telecommunications. responsivities 850, 980, 1310, 1550, 1605 are...

We demonstrate a 0.25% tensile strained Ge p-i-n photodetector on Si platform that effectively covers both C and L bands in telecommunications. The direct band edge of the film has been pushed from 1550 to 1623 nm with strain, enabling effective photon detection whole band. responsivities device at 1310, 1550, 1620 are 600, 520, 100mA∕W under 0 V bias, which can be further improved 980, 810, 150mA∕W antireflection coating based calculations. Therefore, wavelength range used 1310 comparable...

The deformation potential constants at the $\ensuremath{\Gamma}$ point of $\mathrm{Ge}$ epitaxial films on $\mathrm{Si}(100)$ were determined by a combination x-ray diffraction and photoreflectance measurements. in-plane tensile strain in thin was engineered growth different temperatures ultrahigh vacuum chemical vapor deposition backside silicidation. Photoreflectance measurements data analysis give direct band gaps from maxima light- heavy-hole bands to bottom valley, namely,...

Epitaxially grown Ge layers on Si substrate are shown to reveal an enhanced absorption of near-infrared light, which is effective for the photodiode application in Si-based photonics. as thick 1μm were by ultrahigh-vacuum chemical-vapor deposition with a low-temperature buffer layer technique. X-ray-diffraction measurements showed that possesses tensile strain large 0.2%, generated during cooling from high growth temperature due thermal-expansion mismatch between and Si. Photoreflectance...

Tensile strained epitaxial Ge films were grown on Si(100) substrates by ultra-high vacuum chemical vapor deposition. The tensile strain was induced the thermal expansion coefficient mismatch between Si and during cooling process from elevated growth temperatures, which induces narrowing of direct band gap, EgΓ, pushes absorption spectrum toward longer wavelengths. EgΓ versus relation measured experimentally photoreflectance x-ray diffraction, result agrees well with calculations deformation...

Thin films of SiO2 and TiO2 were used to fabricate one-dimensional photonic crystal devices using the sol-gel method: an omnidirectional reflector microcavity resonator. The consisted six SiO2/TiO2 bilayers, designed with a stopband in near infrared. Reflectivity over incident angle range 0°–80° showed band 70 nm, which agrees theoretical predictions for this materials system. resonator Fabry–Perot cavity sandwiched between two mirrors three bilayers each. We have fabricated resonance at...

On the silicon (Si) photonic platform, we monolithically integrated a silica-based arrayed-waveguide grating (AWG) and germanium (Ge) photodiodes (PDs) using low-temperature fabrication technology. We confirmed demultiplexing by AWG, optical-electrical signal conversion Ge PDs, high-speed detection at all channels. In addition, mounted multichannel transimpedance amplifier/limiting amplifier (TIA/LA) circuit on fabricated AWG-PD device flip-chip bonding The results show promising potential...

Recombination-enhanced impurity diffusion (REID) in Be-doped GaAs has been observed for the first time. Current-induced degradation of tunnel diodes investigated. The Be under forward bias is enhanced by a factor about 1015 at room temperature, and activation energy reduced from 1.8 eV thermal to 0.6 REID. RElD Be, which released on minority-carrier injection recombination center could enhance diffusion, thought be origin degradation.

We demonstrate the monolithic integration of germanium (Ge) p-i-n photodetector (PDs) with silicon (Si) variable optical attenuator (VOAs) based on submicrometer Si rib waveguide. A PD is connected to a VOA along waveguide via tap coupler. The PDs exhibit low dark current ~60 nA and large responsivity ~0.8 A/W at reverse bias 1 V room temperature. These characteristics are uniform over chip scale. generate photocurrents precisely respect DC power attenuated by VOAs. Two devices work...

Optical circuits are low power consumption and fast speed alternatives for the current information processing based on transistor circuits. However, because of no function available in optics, architecture optical computing should be chosen that optics prefers. One which is Binary Decision Diagram (BDD), where signal processed by sending an from root through a serial switching nodes to leaf (terminal). Speed limited either transmission time signals or node. We have designed experimentally...

We present a study of the influence high strain on bandgap and refractive index silicon. The results photoluminescence show that with applied, silicon can be adjusted to 0.84 eV increases significantly. 1.4% change was observed. strain-induced shrinkage absorption coefficient are considered as main cause significant change. work indicates application is promising control in devices so applications such compensation thermal effect optical achieved.

Strained InxGa1—xN quantum wells (QWs) on thick GaN base layers were investigated to verify the importance of localized QW excitons in their spontaneous emission mechanisms. A strength internal piezoelectric field (FPZ) across increases with increasing x up 1.4 MV/cm for = 0.25, since in-plain strain increases. For QWs well thickness L greater than 3 nm, FPZ dominates peak energy due quantum-confined Stark effect. Absorption spectra both hexagonal and cubic InGaN exhibited a broad band-tail...

The authors report the first observation of a large, strain-enhanced, electro-optic effect in weakly absorbing regime for Ge epitaxial films grown directly on Si substrates. field dependence absorption was measured from spectral responsivity measurements Ge-on-Si p-i-n diodes. experimental data were analyzed using generalized Franz-Keldysh formalism [H. Shen and F. H. Pollak, Phys. Ref. B 42, 7097 (1990)] valence band edge shifts light- heavy-hole energy positions response to biaxial stress....

Subscale model tests and a numerical investigation are performed to predict attenuate the acoustic level of Epsilon launch vehicle at liftoff. Requirements for subscale test full-scale environment investigated, then scale size is set 1/42. The pads employed herein designed reflection Mach wave radiated from free jet due jet's impinging on flame deflector. When comparing result taken fairing location with that three different altitudes, , where represents nozzle exit diameter, observed...

Ge-on-Si is an attractive material platform for mid-IR broadband sources on a chip because of its wide transparency window, high Kerr nonlinearity and CMOS compatibility. We present low-loss waveguide with flat low dispersion from 3 to 11 µm, which enables coherent supercontinuum 2 12 generated using sub-ps pulsed pump. show that 700-fs pump pulses peak power 400 W are needed generate such supercontinuum, the length around 5.35 mm.

Air trench structures for reduced-size bends in low-index contrast waveguides are proposed. To minimize junction loss, the designed to provide adiabatic mode shaping between low- and high-index regions, which is achieved by introduction of "cladding tapers." Drastic reduction effective bend radius predicted. We present two-dimensional (2-D) finite-difference time-domain/effective index method simulations representative silica contrasts. also argue that substrate while present, can be...