José Luis de Miguel

Spanish National Research Council | CSIC · Institute of Optics "Daza de Valdés"

In this paper we propose and demonstrate two alternative methods for the high-precision calibration of fiber Bragg grating (FBG) interrogators. The first method is based on the direct comparison between the wavelength measurements of the interrogator under test and a calibrated wavemeter, while analyzing a simulated symmetric Bragg grating construc...

Research on aging gave rise to 2.4% of all scientific publications that appeared in 2015 in the world. A proportion that, in the case of Spain, is slightly higher, standing at 2.7% of the total of its scientific production. In the period 2009-2015, the number of publications on aging grew at a rate three times that of publications in all areas of r...

Heteroepitaxial ZnSe grown by molecular beam epitaxy (MBE) has been characterized using low temperature photoluminescence (PL) and reflectance. Excitonic PL linewidths of thick (relaxed) ZnSe layers are>1.4 meV, and depend little on the type of substrate or buffer layer used (e.g. GaAs or AlAs). In contrast, thin (pseudomorphic) ZnSe layers on AlAs...

We have grown ZnSe epitaxial layers on bulk GaAs substrates and on GaAs epitaxial layers, with both As-rich and Ga-rich surface terminations. We have also grown ZnSe on AlAs epitaxial surfaces with different As to Al ratios. In all cases, abrupt, layer-by-layer growth is observed on the As-rich surfaces, while 3-dimensional nucleation is observed o...

Waveguide photodetectors (1.5 /spl mu/m) for polarization diversity coherent receivers have been fabricated on InP and characterized. They make use of the properties of multiquantum wells (MQW) to detect separately the TE and the TM polarized light. Diversity detection is achieved without the use of a polarization splitter or polarization controlle...

The expressions given by the kinematic theory of X-ray diffraction have been particularized to strained layers multiple quantum wells (SL-MQW) of GaInAs/GaInAsP. A procedure based on these expressions is proposed that, with a proper design of the test sample, yields the layer thicknesses and composition of the SL-MQW. This procedure is applied to a...

Simple design formulas for optical power splitters with an arbitrary number of output ports (1*N) are presented. They are obtained using a model based on the interference of the confined modes of a multimode wide section. These formulas provide the correct dimensions of the device, plus the output phase relations and output guides location. The acc...

Citation A. Ferreras, F. Rodriguez, E. Gomez-Salas, J. L. de Miguel, and F. Hernandez-Gil, "Design and Fabrication of a InP/InGaAsP Multimode Power Splitter," in Integrated Photonics Research, Vol. 10 of 1993 OSA Technical Digest Series (Optical Society of America, 1993), paper IME4. http://www.opticsinfobase.org/abstract.cfm?URI=IPR-1993-IME4

A dual back-illuminated photodetector for balanced coherent receivers applications is presented. The photodetectors have an InP/InGaAs/InP p-i-n structure. Several additional semiconductor layers have been added to fabricate the structure by selective wet etching. The material was grown by metalorganic vapor phase epitaxy (MOVPE) on a semiinsulatin...

The development of composite materials incorporating both II‐VI and III‐V compound semiconductors, such as ZnSe and GaAs, leads to the possibility of a variety of new devices of potential importance to the communications industry. In many cases, such as those involving resonant tunneling junctions and quantum well structures, the quality of the int...

We have made cw and time-resolved photoluminescence measurements at high excitation intensity on type II GaAs-AlAs superlattices at low temperature. A new band appears between the Γ and X exciton lines at a threshold power which is dependent on the sample, but is ordorder 1012 electron-hole pairs per cm2 per layer for cw pumping, and 1013 for pulse...

The quality of heteroepitaxial growth of II‐VI materials on III‐V substrates, such as ZnSe on GaAs(100), depends strongly on the atomic structure and stoichiometry of the substrate. We define and describe those structures that optimize heteroepitaxial interface growth on GaAs(100) and related surfaces, and propose specific models for the c(6×4), ‘‘...

Experimental results on 0.3 μm thick (A1As)m(InAs)n superlattices (m, n = 1, 2, 3, 5, 10 monolayers) grown by atomic layer molecular beam epitaxy on (100) GaAs substrates are presented, X-ray and Raman experiments show that they are decoupled from the substrate in the range of composition studied. These results are compared with lattice relaxation...

Low threshold and high efficiency operation of strained layer multiple quantum well InGaAs-InGaAsP lasers at 1.5 micrometres wavelength is demonstrated. Current thresholds as low as 2.2 mA with threshold current densities of 440 A/cm² have been obtained. With 7.3 mA threshold current, quantum efficiency was 65%/front facet. At 20 mW CW o...

InGaAs/InGaAsP multiple quantum well (MQW) lasers at 1.3-1.5 micron wavelength have yielded several advantages over bulk lasers at this wavelength range, such as low internal loss , high quantum efficiency, low threshold current operation and small linewidth enhancement factors [1-3]. There have been several reports predicting that further improvem...

We report electrical characterization of a series of ZnSe samples which are planar doped by a new approach to doping involving periodic deposition of sheets of Ga on Zn‐ or Se‐rich surfaces. For samples planar doped on Zn‐rich surfaces, the mobility could be described by ionized‐impurity scattering and polar optical‐phonon scattering mechanisms, wh...

Room‐temperature and low‐temperature (1.7‐K) photoluminescence (PL) characteristics of heteroepitaxial ZnSe layers on GaAs which are doped with Ga by either conventional (bulk) or planar doping techniques are described. Low‐temperature PL peaks at 2.27 and 2.0 eV involving deep acceptor levels are introduced by Ga doping, as well as newly reported...

The effect of transferring in ultrahigh vacuum conditions between molecular‐beam epitaxy chambers on the quality of regrown interfaces is addressed. In particular, the Al0.35Ga0.65As/GaAs heterointerface is probed by low‐temperature photoluminescence using a single quantum well (SQW) configuration, where the growth of the second interface has been...

A multiple chamber molecular beam epitaxy (MBE) system has been used to investigate a novel material system: GaAs/ZnSe heterostructures. Growth of ZnSe on GaAs shows that two dimensional nucleation of ZnSe occurs only on As rich GaAs surfaces while island growth occurs on the Ga rich surfaces. Studies of the inverted interface, GaAs on ZnSe, reveal...

In this paper we describe results on the growth of ZnSe/GaAs heteroepitaxial structures using a dual chamber molecular beam epitaxy (MBE) system. We have observed a preference for ZnSe to grow on the GaAs (2x4) As rich surface. In addition, we observe one dimensional disorder in the initial nucleation of GaAs when grown on ZnSe layers. We attribute...

A new approach to doping in ZnSe, which involves Ga deposition in spatially separated atomic planes (planar doping), is reported. The dependence of doping efficiency on the particular surface termination (Zn or Se stabilized) maintained during the deposition of the Ga dopant is investigated by Hall measurements and low‐temperature photoluminescence...

We present low‐temperature ZnSe photoluminescence spectra having very narrow bound exciton linewidths (0.55 meV), which demonstrate for the first time that thin, pseudomorphic ZnSe layers with minimal inhomogeneous strain can be grown directly on GaAs by molecular beam epitaxy. Similar characterization of ZnSe/AlAs/GaAs heterostructures shows that...

Using mixtures of boron trichloride and argon, we show it is possible to reactive ion etch epitaxial thin films of ZnSe grown on GaAs. Optimum etching conditions were determined by the application of a model generated from the multiple linear regression of the independent variables affecting the etching process. These variables included the power,...

Des photodiodes p-i-n InAlAs/InGaAs à double hétérostructure ont été produites par MBE et montées sur des guides d'onde coplanaires. Deux méthodes : (i) l'incorporation de couches InAlAs non dopées entre la zone d'absorption InGaAs et les couches InAlAs dopées et (ii) l'utilisation d'hétérojonctions graduelles ont été utilisées pour réduire l'accum...

Epitaxial thin films of ZnSe grown on GaAs substrates were reactive ion etched using BCl3 /Ar gas mixtures. Using an optimized etching process, photolithographically defined micrometer sized structures were etched several micrometers deep with straight sidewalls and smooth surfaces. Cathodoluminescence was measured from both etched and unetched sur...

We demonstrate that a GaAs-AlAs superlattice can be switched from indirect to direct, in both real and reciprocal spaces, by application of a modest axial electric field. The crossover region is found to be an anticrossing, manifesting the presence of GAMMA-X mixing by a potential measured to be of the order of 1 meV. This value is corroborated by...

Strained In 0.52 Al 0.48 As/InAs single quantum wells have been grown by molecular beam epitaxy on InP substrates and their structural quality and commensurability demonstrated by transmission electron microscopy. Intense photoluminescence in the wavelength range of 1.2–1.6 μm for well widths between 10 and 30 Å was obtained, indicating a very effi...

The evolution of the structural and optical quality of molecular‐beam epitaxial (MBE) grown InAs/In 0.52 Al 0.48 As pseudomorphic quantum wells with increasing well thickness has been analyzed by transmission electron microscopy (TEM) and photoluminescence measurements. TEM was used to assess the commensurability of the samples as well as to confir...

We have studied, using reflection high energy electron diffraction (RHEED), the initial growth stages of ZnSe layers grown by molecular beam epitaxy (MBE) on GaAs exhibiting various surface terminations. The structural quality of the ZnSe layers was assessed by transmission electron microscopy (TEM). We have observed a preference for two‐dimensiona...

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We report photoluminescence and photoconductivity measurements on single InAs quantum wells under a 3.4% biaxial compression. The photoluminescence line, which is in the 1.2–1.6 μm wavelength range depending on well thickness, is interpreted as recombination between electrons and holes distributed over a range of confined energy states associated w...

Excitonic resonance structures in GaAs/AlAs multiple quantum well heterostructures with varying barrier-layer thicknessesL B down to 1.3 nm are investigated for two sets of samples with the nominal well widths ofL Z =9.2 and 6.4 nm, by 2K photoluminescence excitation spectroscopy. The observed resonance energies of then=1 heavyhole (1 hh) and light...

We have grown ZnSe epitaxial layers on GaAs bulk substrates and on GaAs epitaxial layers by molecular beam epitaxy (MBE). A dual chamber MBE system was used which enabled the growth of the GaAs/ZnSe heterostructure completely in-situ. Examination of the initial stages of growth using RHEED indicates a much improved interface when ZnSe is grown over...

The influence of Al composition x on the optical properties of AlAs/AlxGa1-xAs multiple quantum well heteroestructures (MQWH) is studied by photoluminescence (PL) and photoluminescence excitation spectroscopy (PLE) at 2 K. Besides the expected high energy shift of the luminescence lines with increasing Al concentration in the wells, broader PL peak...

We have performed photoluminescence, photoluminescence excitation, absorption, and double-crystal X-ray diffraction measurements to study the influence of interface quality, statistical ternary alloy disorder, strain, and residual impurity level on excitonic transitions in quantum wells formed either by binary or ternary III-V semiconductors (GaAs/...

The influence of barrier layer thickness L B for L B ≫3 nm on the optical properties of all‐binary AlAs/GaAs multiple quantum well heterostructures (MQWH) is studied by photoluminescence and excitation spectroscopy measurements at 2 K. In contrast to expectation for a simple coupling between the constituent GaAs quantum wells, MQWH samples with thi...

GaAs single quantum well heterostructures (SQWH) confined by all-binary GaAs/AlAs short-period-superlattices (SPS) and by ternary AlxGa1-xAs alloy were grown by molecular beam epitaxy. The results of detailed photoluminescence measurements under direct and indirect excitation conditions and of excitation spectroscopy measurements at 2 K indicate th...

Analysis of RHEED oscillations under static conditions and during MBE growth has been used to study the surface departure from stoichiometry and related microscopic morphology for the As-stabilized 2× 4 (001)GaAs surface reconstruction when substrate temperature and arsenic pressure are systematically varied. Specular beam intensities under static...

H2S gas has been used during molecular beam epitaxy (MBE) growth of GaAs and Al x Ga1–x As as sulphur vector forn-type doping. Doping efficiencies are less than 10–3 at usual growth temperatures, and are limited by an incorporation competitive surface process, probably 2Ga+H2SGa2S+H2. In AlxGa1–x As forx0.2 the doping efficiency is further reduced...

The possibility of using SiH 4 as a cold source of Si dopant during MBE growth of GaAs and Al x Ga 1-x As has been explored. Layers of these materials grown under SiH 4 doping beam showed good electrical characteristics and LPE quality photoluminescence. Neither accumulation nor memory effects have been observed but the overall doping efficiency is...

Ponencia presentada en el Seminario "Ciencia, tecnología y patentes" celebrado en la UIMP de Santander del 9 al 13 de julio de 2007. La innovación tecnológica es un importante elemento de competitividad en la economía moderna. Existe una correlación positiva entre inversión en I+D y comportamiento económico. Sin embargo, en España el conocimiento c...