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Copyright of Acta Universitatis Carolinae Philologica is the property of Charles University Prague, Karolinum Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Based on the photovoltaic properties and tandem solar cells theory, Gallium Indium Arsenide/Germanium Stannide (GaInAs/GeSn)-based double-junction (DJ) solar cells have been numerically simulated for the first time. In this study, we explore the band gap combination under lattice matching and obtain the content of In/Sn at optimal efficiency, which is expressed as Ga _0.84 In _0.16 As/Ge _0.93 Sn _0.07 DJ solar cell (1.20/0.58 eV). Afterward, it is optimized in terms of variation in the doping contents and active layer thickness. To take full advantage of the electron mobility of the material, the optimal ‘inverted doping profile’ concentration N _a(d) is 1.5(5)/5(20) × 10 ^18 cm ^−3 . In addition, the reasonable p ( n ) layer thickness could be comprised of 0.2–0.8(0.2–1)/0.5–3(1–4) μ m of the DJ solar cells with less material consumption. When the p ( n ) layer thickness is 0.30(0.25)/0.9(1.35) μ m, the tandem device can achieve an optimal efficiency of 31.00% with 28.98 mA cm ^−2 ( J _sc ), 1.25 V ( V _oc ) and 85% ( FF ). This study highlights that GeSn materials have the potential to combine with III–V materials to form low-cost and high-efficiency tandem devices.

This paper deals with the topic of Christian Goths in Constantinople, who, at the turn of the 4th to the 5th century, played an important role in the history of religious matters in the city. A significant part of these were of Arian confession, which was forbidden as heresy from the ascension of Theodosius I. Thanks to the Nicene Christian authors who actively fought Arianism, we are able to reconstruct the development of the Arian Gothic community in Constantinople and its most distinguished members. The topic of Nicene Goths in Constantinople will be presented in a follow-up paper, to be published in the next issue of Graeco-Latina Brunensia. [ABSTRACT FROM AUTHOR]

GaInAs-based Metal Oxide Semiconductor High Electron Mobility Transistors (MOS-HEMTs) can in principle combine the wide bandwidth of HEMTs to the low gate leakage current of MOSFETs in a single deeply-scaled ultrahigh speed low-noise technology. Despite advances in the fabrication of MOS-HEMT devices and MMICs, the transistor microwave noise properties of GaInAs MOS-HEMT devices have not yet been reported. In the present study, the room temperature DC and wideband RF noise properties (8-50 GHz) of GaInAs channel MOS-HEMTs are characterized and contrasted to those of a 50 nm low-noise HEMT with the same channel composition/thickness and similar ${f}_{{\text {T}}}$ : at a given bias ${V}_{{\text {DS}}} = {0.5}$ V, the HEMT provides lower minimal noise figures (${\textit {NF}}_{{\text {MIN}}}$) and higher associated gain. In contrast to HEMTs, the MOS-HEMTs particularly suffer from lower frequency noise contributions attributed to enhanced impact ionization. Remarkably, operation at ${V}_{{\text {DS}}} = {0.4}$ V to mitigate ionization enables MOS-HEMTs to match the HEMT wideband ${\textit {NF}}_{{\text {MIN}}}$ performance despite a significantly poorer low-field channel mobility. The present MOS-HEMTs show the highest reported maximum oscillation frequency ${f}_{{\text {MAX}}} = 637$ GHz for a measured gate length ${L}_{G} = {33}$ nm and a ($2\times15$) $\mu \text{m}$ width. Gate annealing is shown to be deleterious to the MOS-HEMT DC and noise properties. [ABSTRACT FROM AUTHOR]

GaInAs/InAs composite channels in InP-based pHEMTs enable wideband and/or low-noise performances because of their superior carrier transport properties. To date, the influence of the InAs inset design details on transistor performance has not been parametrized in the literature. We present a systematic study of the effects of the InAs channel inset thickness on transistor characteristics and cutoff frequencies versus temperature, and on the noise performance at 300 K. The epitaxial layer structures considered here incorporate 2 to 5-nm InAs insets in a fixed total composite channel thickness. All layers exhibit excellent electron mobilities (from 40 200 to 54 800 cm2/Vs at 77 K). Thicker InAs insets improve both the current gain cutoff frequency (${f}_{\text {T}}$) and the maximum oscillation frequency (${f}_{\text {MAX}}$). However, they also result in higher gate leakage currents and increased channel impact ionization. 50-nm gate length pHEMTs with a 5-nm InAs inset feature the highest simultaneous ${f}_{\text {T}} / {f}_{\text {MAX}} \ge {390}$ /675 (455/800) GHz at 300 (15) K for a low-noise bias but exhibit the poorest minimum noise figure ${NF}_{\text {MIN}}$. Whereas higher ${f}_{\text {T}}$ (and/or ${f}_{\text {MAX}}$) values have traditionally been associated with improved noise performances, this is no longer the case. [ABSTRACT FROM AUTHOR]

A prototype In _0.53 Ga _0.47 As p ^+ -i-n ^+ x-ray photodiode, fabricated from material grown by metalorganic vapour phase epitaxy, was investigated as a novel detector of x-rays. The detector was connected to a custom low-noise charge sensitive preamplifier and standard readout electronics to produce an x-ray spectrometer. The detector and preamplifier were operated at a temperature of 233 K (−40 °C). An energy resolution of 1.18 keV ± 0.06 keV Full Width at Half Maximum at 5.9 keV was achieved. This is the first time InGaAs (GaInAs) has been shown to be capable of spectroscopic photon counting x-ray detection.

Synesius, bishop of Ptolemais, played an important role in the intellectual life of the Roman Empire on the turn of IV–V centuries. The article is devoted to the life and activity of Synesius in the context of his literary works that reflected the main milestones of the transition period. This article also focuses on Synesius` political and social views, which had a great impact on formation of anti-barbarian moods in the Late Ronan society.

Lattice-matched GaInAs p-i-n diodes of different i-region thicknesses have been MBE grown on n-type InP (100) and (111) crystallographic orientation substrates. It has been found that terahertz emission from such structures when illuminated with femtosecond laser pulses can be more efficient than that from the known to date best surface terahertz emitter (111) p-InAs. The explanation of the terahertz generation mechanism from p-i-n diodes is based on ultrafast photocurrent effects. Anisotropic transient photocurrents causing the azimuthal angle dependence are observed in the sample on (111) substrate. These p-i-n structures allow covering a technologically important 1.55,wm range and may provide controllability and compactness of a THz- TDS system when biased with an external voltage source. [ABSTRACT FROM AUTHOR]

We report on the electronic transport properties of p-modulation Be-doped Ga0.8In0.2As/GaAs single quantum well. The experiments included the spectral photoluminescence between 8 and 300?K, and Hall effect measurements at temperatures between 14 and 300?K. The effect of strain which induces splitting of the valence band as light and heavy hole bands on transport is discussed. The calculated band alignment of the GaInAs sample using model-solid theory including strain effects indicates large conduction band discontinuities and a much smaller valance band discontinuity in GaInAs. The effect of the conduction and valance band discontinuity on the electronic transport properties is also discussed. [ABSTRACT FROM PUBLISHER]

Type-II InP-based light sources provide a promising concept for mid-infrared lasers. These have recently made huge progress, as the first electrically and optically pumped lasers could be demonstrated beyond the wavelength limit for type-I InP-based lasers (∼2.3 μm). In this paper, we introduce the material system and device concepts, and report the latest achievements, such as electrically pumped lasing operation up to a wavelength of 2.6 μm in pulsed mode, continuous-wave resonant-cavity light-emitting diode operation up to a wavelength of 3.3 μm at 20–80 °C and photoluminescence even up to 3.9 μm. [ABSTRACT FROM PUBLISHER]

Abstract: X-ray diffraction (XRD), current–voltage (IV), capacitance–voltage (CV), deep-level transient Fourier spectroscopy (DLTFS) and isothermal transient spectroscopy (ITS) techniques are used to investigate the thermal annealing behaviour of three deep levels in Ga0.986In0.014As heavily doped with Si (6.8×1017 cm−3) grown by molecular beam epitaxy (MBE). The thermal annealing was performed at 625°C, 650°C, 675°C, 700°C and 750°C for 5min. XRD study shows good structural quality of the samples and yields an In composition of 1.4%. Two main electron traps are detected by DLTFS and ITS around 280K, with activation energies of 0.58eV and 0.57eV, capture cross sections of 9×10−15 cm2 and 8.6×10−14 cm2 and densities of 2.8×1016 cm−3 and 9.6×1015 cm−3, respectively. They appear overlapped and as a single peak, which divides into two smaller peaks after annealing at 625°C for 5min. Annealing at higher temperatures further reduces the trap concentrations. A secondary electron trap is found at 150K with an activation energy of 0.274eV, a capture cross section of 8.64×10−15 cm2 and a density of 1.38×1015 cm−3. The concentration of this trap level is also decreased by thermal annealing. [Copyright &y& Elsevier]

A novel scheme for polarization insensitive GaInNAs-based semiconductor optical amplifiers is proposed in which TE and TM polarization gain is almost equal for GaInNAs quantum wells with GaInAs barriers. The proposed scheme involves the growth of GaInAs metamorphic layers on GaAs. Based on a k ∙ p Hamiltonian that accounts for the N-induced modifications of the bandstructure, we calculate the optical properties of GaInNAs-GaInAs quantum wells and explore the effect of GaInAs barriers on the valence band mixing effects. The TE and TM amplifier gain of GaInNAs-based semiconductor optical amplifiers with GalnAs barriers is then analyzed. [ABSTRACT FROM AUTHOR]

Surface recombination effects are studied in non-passivated non-self-aligned and self-aligned NpN InP-GaAsSb-InP double heterostructure bipolar transistors (DHBTs) down to sub- micrometer emitter dimensions, and over current densities ranging from 10 A/cm² to 100 kA/cm². The present study is motivated by the drive to scale InP DHBTs for higher speeds and integration densities. Self-aligned InP-GaAsSb-InP DHBTs are characterized by weak emitter size effects (ESEs), and periphery recombination currents are found to be very nearly identical to published results for InP-GaInAs SHBTs despite the major differences in emitter junction band alignments ("type-II" versus "type-I") and injection mechanisms (thermal versus hot electron injection). The correspondence of measured periphery currents in both systems indicates that ESEs are dominated by a mechanism common to InP-GaAsSb and InP-GaInAs devices: this requirement is fulfilled by the direct electron injection from the InP emitter mesa sidewalls onto the extrinsic base surface. Consideration of band alignments and surface depletion effects at the extrinsic base surface is used to explain the commonality of emitter size effects in InP-GaAsSb and InP-GaInAs devices. [ABSTRACT FROM AUTHOR]

Today, most infrared focal plane arrays (FPAs) utilize a hybrid scheme. To achieve higher device reliability and lower cost, monolithic FPAs with Si based readout integrated circuits (ROICs) are the trend of the future development. In this paper, two approaches for monolithic FPAs are proposed: double sided integration and selective epitaxy integration. For comparison, the fabrication process for hybrid quantum well infrared photodetectors (QWIP) FPAs are also described. Many problems, such as the growth of QWIPs on Si substrate and processing incompatibility between Si and III–V semiconductors, need to be solved before monolithic FPAs can be realized. Experimental work on GaInAs/InP QWIP-on-Si is given in this paper. A record high detectivity of 2.3 × 109 cm Hz1/2/W was obtained for one QWIP-on-Si detector at 77 K. [Copyright &y& Elsevier]

Energy loss rates of two-dimensional electron gas in GaInAs/AlInAs, InSb/AlInSb and GaSb/AlGaAsSb heterostructures are theoretically investigated over a wide range of temperature based on the electron–one-phonon and electron–two-phonon interactions. Calculations are presented for electron acoustic one-phonon interaction via deformation potential and piezoelectric coupling and electron–LO phonon interaction with hot phonon effect. In addition, energy loss rate due to electron-two-zone edge transverse acoustic (TA) phonons is also presented. A very good agreement is obtained between the calculations and experimental data in GaInAs/AlInAs structure with the inclusion of electron–two-zone edge TA phonon interaction. In all these three structures energy loss is dominated by (i) acoustic one-phonon scattering at low temperatures, (ii) two-TA zone edge phonons at intermediate temperatures and (iii) LO phonons at high temperatures. It is observed that, hot phonon effect reduces the energy loss rate considerably in these structures. [Copyright &y& Elsevier]

VCSELs are an important technology with many characteristics such as high modulation bandwidth, low-threshold currents and single-mode behaviour that make them suitable for telecommunications applications. InGaAsP/InP is one material system that has been used to manufacture devices that operate in the 1.55 μm region. However, the room temperature performance of VCSELs using this material system fall below those devices using AlGaAs/GaAs operating at shorter wavelengths. Therefore, it is of interest to investigate the temperature dependence of these long wavelength devices. In this paper we describe the experimental results on an array of 64 InGaAsP/InP VCSELs and ultra-bright LEDs designed to emit at 1.5 μm. We also take a simple theoretical model and compare the results with theory. [Copyright &y& Elsevier]

Strained AlxIn1−xAs/Ga0.47In0.53As heterojunction N-p+ diodes and heterojunction bipolar transistors (HBTs) have been grown on InP substrates by solid-source molecular-beam epitaxy, fabricated, and characterized. To determine the effects of the conduction-band discontinuity at the emitter-base heterojunction on turn-on voltage and ideality factor, a strained Al0.7In0.3As layer is inserted in the emitter near the base. Changes in transport across the junction are observed as a function of the strained-layer position and thickness. These results were used to implement strained emitter HBTs. [ABSTRACT FROM AUTHOR]

Lattice-mismatched Ga1−xInxAs solar cells with an absorption edge between 900 and 1150 nm have been grown on GaAs substrates. Different graded Ga1−xInxAs buffer layers and solar cell structures were evaluated to achieve a good electrical performance of the device. External quantum efficiencies comparable to our best GaAs solar cells were measured. The best 1 cm2 cell with a bandgap energy of 1.18 eV has an efficiency of 22.6% at AM1.5g and a short circuit current density of 36.4 mA/cm2. To our knowledge, this is the highest reported efficiency for a Ga0.83In0.17As solar cell. [ABSTRACT FROM AUTHOR]

We have grown GaInAs:C by low pressure organometallic vapor phase epitaxy and observed that the hole concentration of such layers decreases upon growth of cap layers such as heterojunction bipolar transistor emitter layers. Two mechanisms were found to play a role: one is H repassivation of the C acceptors, the other a non-H related decrease in the concentration of C acceptors due to C changing site or to the formation of complexes involving C. Depending on the growth conditions of the cap layers (temperature, flow of group V sources), one or the other mechanism prevails. [ABSTRACT FROM AUTHOR]

The growth and characterization of strained GaInAs and GaInAsP multiquantum well (MQW) laser structures has been investigated. The use of triple axis x-ray diffraction (XRD), in addition to the conventional high resolution double crystal XRD, yields further information about the structural integrity of these complex structures. Buried heterostructure lasers with eight GaInAsP wells (+1.0% strain, 80Å thick) exhibit a record low threshold current of 3.1 mA. By using a constant As/P ratio in the wells and barriers of an MQW laser structure, we have shown that the structure can be annealed at 700°C for 1 h with only a minimal shift (-4 nm) in the photoluminescence emission wavelength. Conventional lattice-matched GaInAs/GaInAsP MQW structures exhibit a shift of-46 nm under the same conditions. [ABSTRACT FROM AUTHOR]

High-quantum-efficiency, lattice-mismatched, 1.0-eV GaInAs solar cells grown by organometallic vapor phase epitaxy have been developed for ultimate integration into AlGaAs/GaAs/GaInAs 3-junction, 2-terminal monolithic devices. The more standard n/p junction was replaced with an n-i-p structure in the GaInAs cell in order to increase the short-circuit current by overcoming the material deficiencies which arise as a result of accommodating the lattice mismatch. This led to single junction 1.0-eV GaInAs cells with internal quantum efficiencies >90% and short-circuit-current densities that match or closely approach those needed to current match the upper AlGaAs and GaAs cells. A 4.1% (1-sun, air mass 0,25°C) power conversion efficiency was achieved with a developmental structure, indicating the potential of the lattice-mismatched n-i-p 1.0-eV GaInAs cell. An analogous device designed to allow direct monolithic integration with the upper AlGaAs and GaAs cells, with a modified grading layer of AlGaInAs in place of the usual GaInAs, achieved an efficiency of 2.2%, primarily due to a lower open-circuit voltage. The open-circuit voltage is perhaps limited by structural defects revealed in transmission electron micrographs. [ABSTRACT FROM AUTHOR]

This paper presents a study of the structural and optical properties of strained GaInAs/ InP multiple quantum well (MQW) structures fabricated by LP-MOVPE. The composition of the GaInAs films ranged from x = 0.17 to x = 1.0 and was determined by sputtered neutral mass spectrometry (SNMS) on thick layers. The structures of the MQW samples with well widths from 1.5 to 5 nm were investigated by high resolution x-ray diffraction (HR-XRD). Simulations of the diffraction patterns showed that transition layers of approximately 2 monolayer (ML) thickness with high lattice mismatch exist at the interfaces. Photoluminescence (PL) measurements indicate well widths of a multiple of a monolayer with local variations of one monolayer. The PL peak energies vary smoothly with the Ga concentration. These results were confirmed by optical absorption measurements. [ABSTRACT FROM AUTHOR]

The uniformity of InP and GalnAs lattice matched to InP has been studied for three different types of horizontal reactors. Employing the conventional approach, i.e. the susceptor is positioned in the centre or at the bottom of the reactor cell with the wafer surface facing upward, the uniformity in film thickness and ternary composition perpendicular to the direction of gas flow could be substantially improved by using an obstacle which spreads the incoming gas over the entire width of the reactor. In the direction of flow however, a compositional grading of the GalnAs films was observed. This gradient could be avoided by using a novel design in which the substrate is located at the highest and hottest point of the reaction cell and facing downwards. [ABSTRACT FROM AUTHOR]

We report the organometallic vapor phase epitaxial (OMVPE) growth of InP and GaInAs using a new organometallic indium source, ethyldimethylindium (EDMIn), rather than the traditional sources triethylindium (TEIn) or trimethylindium (TMIn). EDMIn is a liquid at room temperature and its vapor pressure at 17° C was found to be 0.85 Torr using thermal decomposition experiments. The growth results using EDMIn were compared to those using TMIn in the same atmospheric pressure reactor. For InP, use of EDMIn resulted in a high growth efficiency of 1.3 × 10 μm/ mole, which was independent of the growth temperature and comparable to the growth efficiency obtained with TMIn. The high growth efficiency is consistent with the observation of no visible parasitic gas phase reactions upstream of the substrate. The 4K photoluminescence (PL) spectra consist of a peak due to bound excitons and an impurity related peak 38 meV lower in energy. This impurity peak is ascribed to conduction band to acceptor transitions from carbon, due to the decreasing relative intensity of this peak with increasing V/III ratio. The relative intensity of the C impurity peak decreases by five times when the growth temperature is increased from 575 to 675° C, with a corresponding increase in the room temperature electron mobility from 725 to 3875 cm/ Vs. For GalnAs lattice-matched to InP, use of EDMIn also resulted in a temperatureindependent high growth efficiency of 1.0 x 10 μm/mole, indicating negligible parasitic reactions with AsH. The In distribution coefficient was nearly constant at a value of 0.9, however the run to run composition variation was slightly higher for EDMIn than for TMIn. The 4K PL showed donor-acceptor pair transitions due to C and Zn. The C impurity peak intensity decreased dramatically with increasing growth temperature, accompanied by an increase in the room temperature electron mobility to 5200 cm/Vs. Overall, the growth of both InP and GalnAs using EDMIn was qualitatively similar to that using TMIn, although the room temperature electron mobilities were lower for the new source than for our highest purity bottle of TMIn. [ABSTRACT FROM AUTHOR]

High quality InP and Ga InAs layers have been grown on InP substrates using MOVPE growth at atmospheric pressure. Excellent material quality has been obtained using triethylindium and trimethylgallium sources (n = 1.7 10 cm, μ = 106 000 cmVs at 77 K for InP and n = 1 − 3 10 cm, μ = 75 000 cmV s at 77 K for GaInAs). The InP/GaInAs interface width obtained is very small (10 Å). The first PIN diodes grown by the process exhibit excellent characteristics. [ABSTRACT FROM AUTHOR]

A number of factors contribute to the high n-type background carrier concentration (high 10 to low 10 cm) measured in MBE GaInAs lattice-matched to InP. The results of this study indicate that the outdiffusion of impurities from InP substrates into GalnAs epitaxial layers can account for as much as two-thirds of the background carrier concentration and can reduce mobilities by as much as 40%. These impurities and/or defects can be gettered at the surfaces of the InP by heat treatment and then removed by polishing. The GalnAs epitaxial layers grown on the heat-treated substrates have significantly improved electrical properties. Hall and SIMS measurements indicate that both donors and acceptors outdiffuse into the epitaxial layers during growth resulting in heavily compensated layers with reduced mobilities. The dominant donor species was identified by SIMS as Si, and the dominant acceptors as Fe, Cr and Mn. [ABSTRACT FROM AUTHOR]

High quality GaInAs, lattice matched to InP, has been reproducibly grown by organometallic vapor phase epitaxy using trimethylgallium (TMGa), trimethylindium (TMIn), and AsH in an atmospheric pressure reactor with no observable adduct formation. For the first time, using TMIn, room temperature electron mobilities of 10 cm/Vs and 77 K mobilities greater than 4 × 10 cm/Vs have beep obtained. Residual donor doping densities in the low 10 cm range have been routinely obtained. Material with excellent morphology has been grown from 540 to 670 C with the highest quality material being obtained near 650 C. The 4 K photoluminescence (PL) peak due to carbon is not seen in the material grown at higher temperatures; however, it increases dramatically as the growth temperature is lowered. This increased carbon incorporation leads to a sharp drop in the electron mobility, which exhibits a T behavior between 77 and 300 K. With optimum growth conditions, 4 K PL halfwidths of 4-5 meV are commonly observed. This high quality material is characterized by x-ray diffraction, PL, and Hall mobility measurements. Carbon and other impurity incorporation as a function of the growth parameters will be described. [ABSTRACT FROM AUTHOR]

Conditions for growth at 550°C of high structural quality GaInAs by LPMOCVD are presented. The sensitivity of compositional grading to changes in the V/III molar ratio, growth rate and inclusion of InP buffer layers is discussed. Crystalline uniformity is indicated by double crystal x-ray rocking curves with FWHM (GaInAs) = 0.017°. By careful control of the V/III molar ratio, epitaxial GaInAs/InP heterostructures with δa/a ≤ 10 can be grown. Quantitative data for the TEIn-AsH elimination reaction rate is presented. The composition of GaInAs which is expected in the presence of this reaction is calculated; evaluation of the corresponding rate constant shows that the adduct formation reaction proceeds at a modest but detectable rate. The problems associated with the purity of electronic grade triethylindium (TEIn) are addressed. Impurities in commercial TEIn have been determined by low resolution mass spectroscopy. [ABSTRACT FROM AUTHOR]

The low pressure metalorganic chemical vapor deposition epitaxial growth and characterization of InP, GaIn As and GaInAsP, lattice-matched to InP substrate are described. The layers were found to have the same etch pit density (EPD) as the substrate. The best mobility obtained for InP was 5300 cm VS at 300 K and 58 900 cm V S at 77K, and for GaInAs was 11900 cm V S at 300 K, 54 600 cm V S at 77 K and 90 000 cm VS at 2°K. We report the first successful growth of a GaInAs-InP superlattice and the enhanced mobility of a two dimensional electron gas at a GaInAs -InP heterojunction grown by LP-MO CVD. LP MO CVD material has been used for GaInAsPInP, DH lasers emitting at 1.3 um and 1.5 um. These devices exhibit a low threshold current, a slightly higher than liquid phase epitaxy devices and a high differential quantum efficiency of 60%. Fundamental transverse mode oscillation has been achieved up to a power outpout of 10 mW. Threshold currents as low as 200 mA dc have been measured for devices with a stripe width of 9 um and a cavity length of 300 um for emission at 1.5 um. Values of T in the range 64-80 C have been obtained. Preliminary life testing has been carried out at room temperature on a few laser diodes (λ = 1.5μm). Operation at constant current for severalthousand hours has been achieved with no change in the threshold current. [ABSTRACT FROM AUTHOR]

GaInAs films have been grown by molecular beam epitaxy (MBE) on InP substrates. The unintentionally doped material has a free electron concentration of 8 × 10cm and exhibits sharp (~5 meV linewidth) exciton recombination in the 4K photoluminescence. The films were grown on (100) InP surfaces which were thermally cleaned in the arsenic beam. The effects of the substrate temperature during growth, the Ga to In flux ratio and the group V to group III flux ratio on the 4K photoluminescence are reported. [ABSTRACT FROM AUTHOR]

Compositionally uniform GaInAs epitaxial layers with 0 ≤ x ≤ 0.2 5 have been grown by organometallic VPE on ◃100▹ GaAs substrates. Compositional uniformities of ±0.25 InAs percentage and ±5% thickness over a 3-cm long wafer have been achieved and are essentially independent of small changes in reactor geometry such as the angle of the susceptor tilt or wafer position on the susceptor. Growth has also been demonstrated at x = 0.52. The GaInAs is grown using trimethylgallium (TMGa), triethylindium (TEIn) or trimethylindium (TMIn), and trimethylarsenic (TMAs). The use of TMAs eliminates the roomtemperature gas-phase reaction between AsH and either TEIn or TMIn, and allows one atmospnere pressure growth conditions to be used without any special mixing arrangements in the reactor. The comparative effects of using TEIn or TMIn as the In source are discussed in terms of crystal quality. Data on crystal composition as a function of gas phase composition and growth rate as a function of composition are presented, and n doping and carrier mobilities and p doping of GaInAs ars characterized. The vapor pressure of TMIn at 0°C is determined to be 0.21 mmHg. [ABSTRACT FROM AUTHOR]

High purity GaIn As has been grown lattice matched on <111>B InP by liquid phase epitaxy. Silicon, the residual impurity, is purged from the melt by long time baking in a hydrogen atmosphere with slight ambient water vapor concentration. Epitaxial layers with a net electron concentration as low as 3.5 × 10 cm and a liquid nitrogen mobility of 70,000 cm/Vsec have been grown. The room temperature mobility is shown to be significantly higher than GaAs over a wide range of net electron concentrations useful for device applications, with the highest value of μ = 13,800 cm/Vsec on a sample with n = 1.9 × I0 cm [ABSTRACT FROM AUTHOR]

We demonstrate an AlInAs–InGaAs separate absorption, grading, and multiplication avalanche photodiode (APD) with a very thin avalanche layer operating at 1550 nm for 10-Gb/s optical transmission achieving simultaneously high responsivity (0.9 A/W at M = 1), very low excess noise factor (F(M=10) = 3), and very high gain-bandwidth product of 240 GHz. To our knowledge, this is the first time that a back-side illuminated planar junction AlInAs–InGaAs APD achieved such performances. [ABSTRACT FROM PUBLISHER]

Abstract: We observe a strong saturation of the carrier density in the quantum well of a MISFET at positive gate voltages. Using a self-consistent Schrödinger/Poisson solver, we model the band structure and find that the saturation is caused by the population of charge states between the gate and the quantum well. We discuss the impact of these charge states on the transport properties, and present a fabrication method that avoids parallel conduction in this heterostructure. [Copyright &y& Elsevier]

An investigation of the recovery dynamics of semiconductor optical amplifiers (SOAs) explains why the ultrafast component of the gain recovery is largely absent in the phase response. The time-resolved gain and phase dynamics of a bulk GaInAs SOA are measured using a pump-probe technique and differences between the gain and phase recoveries are highlighted and explained using Kramers-Kronig analysis. These have important implications for optical signal processing. [ABSTRACT FROM PUBLISHER]

Type-II InP/GaAsSb/InP double heterojunction bipolar transistors (DHBTs) with a 15-nm base were fabricated by contact lithography: 0.73 × 11 μm² emitter devices feature fT = 384 GHz (fMAX = 262 GHz) and BVCEO = 6 V. This is the highest fT ever reported for InP/GaAsSb DHBTs, and an "all-technology" record fT × BVCEO product of 2304 GHz·V. This result is credited to the favorable scaling of InP/GaAsSb/InP DHBT breakdown voltages (BVCEO) in thin collector structures. [ABSTRACT FROM AUTHOR]

Type-II InP/GaAsSb/InP double heterojunction bipolar transistors (DHBTs) with a 15-nm base were fabricated by contact lithography: 0.73 × 11 μm² emitter devices feature fT = 384 GHz (fMAX = 262 GHz) and BVCEO = 6 V. This is the highest fT ever reported for InP/GaAsSb DHBTs, and an "all-technology" record fT × BVCEO product of 2304 GHz·V. This result is credited to the favorable scaling of InP/GaAsSb/InP DHBT breakdown voltages (BVCEO) in thin collector structures. [ABSTRACT FROM AUTHOR]