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Situs inversus totalis is an uncommon anatomical congenital anomaly characterized by complete transposition of viscera with right-to-left reversal across the sagittal plane. Consequently, surgery in such cases is more technically challenging and requires a complete reorientation of visual-motor coordination skills. We describe a case of a 50-year-old gentleman with locally advanced lower esophagus carcinoma post-neoadjuvant chemoradiotherapy with situs inversus totalis and treated with minimally invasive McKeown esophagectomy using a left thoracoscopic, laparoscopic-assisted and right cervical approach. The operative procedure and difficulties during surgery are highlighted. Minimal invasive esophagectomy is safe and feasible in situs inversus totalis. Recognition of the anatomy with a meticulous preoperative planning is advocated for an uneventful operative intervention.

An experiment was executed to test the hypothesis that supplementation of dietary threonine (d-Thr), above NRC recommendation to diets containing poorly digestible protein source (PS) may compensate its detrimental effects on overall performance of broilers. In total, nine hundred 1-day-old mixed sex broilers (Ross-308) were randomly distributed over 6 (2 × 3) experimental diets comprising 5 replicates of 30 broilers each for 35 d. The experimental diets contain either soybean meal (SBM) or canola meal (CM) with 3 levels (100, 110, and 120% of NRC recommendation) of d-Thr. During the course of the trial (0 to 35 D), interactions (P < 0.05) between PS and d-Thr were observed for feed intake (FI), body weight gain (BWG), feed conversion ratio (FCR), carcass, and gut health parameters. The broilers fed recommended level (100%) of d-Thr had 7 and 5% poorer FCR compared with those fed diets with 110 and 120% d-Thr, respectively. For villus height (VH), an interaction (P = 0.007) was found between PS and d-Thr level. Broilers consuming SBM diets had 22% longer villi, 10% deeper crypts, and 30% greater VH to crypt depth ratio (VCR) compared to those fed CM. The broilers fed 110% d-Thr diets had 9% lower crypt depth (CD) and 15% greater VCR compared with those fed diets containing NRC recommended levels. CM resulted in 9% lower protein digestibility with lower (P < 0.05) of some AA, whereas it was improved by 7% in broilers fed 120% d-Thr supplemented diets. The bursa and spleen weights were positively affected (P < 0.001) by PS. Threonine supplementation (10%) resulted in 25% greater thymus, 18% heavier bursa, and 30% greater infectious bursal disease titer. In conclusion, supplementation of d-Thr, above NRC recommendation, resulted in a better growth performance and carcass traits, improved ileal digestibility of protein and amino acids, better gut health, and immunity in broilers.

SUMMARY Millet, an indigenous grain in the Indo-Pak subcontinent, is used as an energy source in poultry diets. There are several varieties of millet, each having specific value of dry matter, apparent metabolizable energy (AME), and crude protein for poultry. Other extrinsic (growing conditions, storage) and intrinsic (carbohydrates and protein contents) factors also influence its AME, digestibility, and hence poultry performance. This review provides a synopsis of those factors that influence the nutritive value of millet regarding its origin (variety, growing conditions, and post-harvest storage), its chemical composition (carbohydrates and protein), physical form of the grain (whole grain or mash), and their influence on zootechnical performance in poultry.

Journal of Instrumentation 15(5), P05023 (2020). doi:10.1088/1748-0221/15/05/P05023, Published by Inst. of Physics, London

This study was primarily designed to evaluate the effect of different concentrations of ultraviolet (UV)-C-irradiated chicken egg yolk plasma (EYP; v:v; 10%, P1; 15%, P2; 20%, P3) or 20% (v:v) of whole chicken egg yolk (WCEY) in tris-citric acid (TCA) extender on water buffalo sperm quality during cryopreservation (postdilution, PD; postequilibration, PE; post-thawing, PT). Also the effect of best evolved concentration of UV-C-irradiated EYP in extender on in vivo fertility of buffalo spermatozoa was evaluated. At PE and PT, computer-assisted sperm analysis progressive motility (PM, %) was significantly higher in P3 compared with P1 and WCEY. Rapid velocity (RV, %) was higher (P0.05) in P3 compared with P1 and WCEY during cryopreservation (PD, PE, and PT). Average path velocity (μm/s) and straight line velocity (μm/s) were higher (P0.05) in P2 and P3 than WCEY at PE and PT. The decline percentage (%, longevity) in PM and RV was lower (P0.05) in P3 compared with WCEY during 2 hours incubation under in vitro condition at PT. Supravital plasma membrane integrity (%) was higher (P0.05) in P2 and P3 compared with control at different stages (PE and PT). Mitochondrial transmembrane potential (%) was higher (P0.05) in P2 and P3 compared with P1 and WCEY at different stages (PD and PT). Percentage of viable sperm with intact acrosome, and sperm DNA integrity (%) were higher (P0.05) in P2 and P3 compared with WCEY at PT. The in vivo fertility rate (%) was significantly higher with P3 compared with WCEY (76.61 vs. 64.49). In conclusion, WCEY (20%) can be replaced with UV-C-irradiated chicken EYP (20%) in TCA extender for cryopreservation of water buffalo spermatozoa.

The current study was designed to investigate the effect of solvents on chemical composition and antidiabetic activity of Zizyphus mauritiana and Acacia Arabica extracts. Total five solvents were used for this purpose (100% methanol, 50% aqueous methanol, 100% ethanol, 50% aqueous ethanol and aqueous). The data obtained from the investigation was subjected to the statistical analysis by using analysis of variance technique. The present study revealed that maximum antioxidant activity was attributed to Acacia arabica (96.53 ± 0.46%) followed by Zizyphus mauritiana (94.33 ± 0.52% by 50% aqueous ethanol extracts). Maximum total phenolic content of both Zizyphus mauritiana and Acacia arabica (670.83 ± 1.46 mg GAE/100g and 934.34 ± 0.89 mg GAE/100g) were shown by 50% aqueous ethanol extracts while maximum total flavonoid content (146.36 ± 0.81 mg QE/100 g, 172.52 ± 0.99 mg QE/100 g) was exhibited by 50% aqueous ethanol extract. The maximum (IC 50= 49.63 ± 0.12 µg/mL) antidiabetic activity was found in aqueous extract of Acacia arabica while in Zizyphus mauritiana the aqueous extract indicated excellent (IC 50= 46.90 ± 0.23 µg/mL) antidiabetic activity.

Triple-GEM detector technology was recently selected by CMS for a part of the upgrade of its forward muon detector system as GEM detectors provide a stable operation in the high radiation environment expected during the future High-Luminosity phase of the Large Hadron Collider (HL-LHC). In a first step, GEM chambers (detectors) will be installed in the innermost muon endcap station in the $1.6, Comment: 23 pages, 24 figures

The present study was carried out to assess various postthaw semen quality parameters for the prediction of fertility in buffalo bull during low-breeding season. Semen (30 ejaculates) was collected from five adult buffalo bulls with artificial vagina (42 °C). Sperm motility parameters, velocity distribution, motion kinematics, and subpopulations were analyzed by computer-aided sperm motion analyzer (CASA). Moreover, sperm visual motility, supravital plasma membrane integrity, viability/acrosome integrity, viability/mitochondrial transmembrane potential, DNA fragmentation/integrity, and morphology were analyzed by phase-contrast microscope, supravital hypoosmotic swelling test, Trypan blue/Giemsa staining, propidium iodide/"5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolyl carbocyanine iodide" (JC-1) fluorochromes, neutral comet assay/acridine orange assay and wet mount technique, respectively. Outcome of 528 inseminations was analyzed for in vivo fertility. Pearson's correlation coefficients revealed that sperm progressive motility (%), rapid velocity (%), average path velocity (μm/s), straight line velocity (μm/s), subpopulation one (most rapid, and progressive) of motile spermatozoa (%), supravital plasma membrane integrity (%), and viable spermatozoa with intact acrosome (%) were significantly correlated with in vivo fertility (r = 0.64, P 0.01; r = 0.57, P 0.01; r = 0.52, P 0.01; r = 0.56, P 0.01; r = 0.73, P 0.001; r = 0.74, P0.001; r = 0.88, P0.001); whereas nonviable spermatozoa with damaged acrosome or low-mitochondrial transmembrane potential and comet length (μm) of neutral comet assay were negatively associated with in vivo fertility (r = -0.79, r = -0.75, P 0.001, and r = -0.60, P 0.05, respectively). Multiple regression analysis reported that combination of semen quality parameters as predictor of fertility were better (R(2) adjusted = 81.30%, P 0.001) as compared with single parameter (R(2) adjusted = 50.20%, P 0.007). It is concluded that assessment of CASA parameters and some other sperm structural and functional parameters, that is, integrity of plasma membrane and acrosome, and transmembrane potential of mitochondria were able to predict the in vivo fertility of water buffalo bull during low-breeding season.

We presented the rapid diagnostic test for dengue infection based on light spectrum of human blood. The transmission spectra of dengue infected whole blood samples have been recorded in ultra violet to near infrared range (400 – 800 nm) of about 30 conformed infected patients and compared to normal blood samples. Transmission spectra of dengue infected blood illustrate a strong band from 400 – 600 nm with prominant peaks at 540 and 580 nm, where is in case of normal blood below 600 nm, total absorption has been observed. These prominent peaks from 400 – 600 nm are characteristics of cells damage and dangue virus antibodies immunoglobulin G (IgG) and immunoglobulin M (IgM) produced against dengue antigen. The presented diagnostic method is non invasive, cost effective, easy and fast screening technique for dengue infected patients.

Sorption studies of chromate on weakly basic macroporous anion exchanger Amberlyst A-21 were performed as a function of pH (2 - 9), temperature (20 - 40 degrees C) and concentration (0.4 - 80 mmol.l(-1)). Chromate sorption was observed to decrease with the increase in initial pH of the solution, with a sorption maxima at pH 2 and increased with the increase in temperature. The changes in pH and in the ratio of choride ions released to chromate ions sorbed suggested that the anion exchange process was accomanied by hydrolysis and Donnan invasion. The FTIR spectra and isoeteric heat of sorption besides showing the hydrolysis / Donnan invasion of resin under different experimental conditions of concentration, pH and temperature also showed the dimerization of the chromate species inside the resin phase.

Sorptionbehavior of metal(III) phosphates toward Zn(2+) was investigated using different concentrations, pHs, and temperatures. Ion exchange between protons from the surface and metal cations from solutions was found to be responsible for metal sorption by metal(III) phosphates. Dissociation constants of metal(III) phosphates and binding constants of the Zn(2+) with metal(III) phosphates were determined using Henderson-Hasselbach and modified Langmuir equations, respectively. The sorption process in all the three metal phosphates was found to be endothermic in nature while the dissociation process was observed to be endothermic in AlPO(4) and FePO(4) and exothermic in CrPO(4). Copyright 1999 Academic Press.

Alkali metal ion exchange (Li + , Na + and K + ) on iron(III) phosphate (FePO 4 ) was studied potentiometrically as a function of temperature and metal ion concentration. The uptake behaviour of iron(III) phosphate was inferred from a comparison of the K + ions sorbed and the loss of H + ions from the exchanger. FT-IR spectroscopic studies and dissolution studies of FePO 4 confirmed the uptake mechanism of alkali metal cations as cation exchange. The potentiometric titration data were employed to evaluate the apparent dissociation constants of iron(III) phosphate which were found to depend on the temperature of the system. The corresponding thermodynamic parameters ΔH 0 and ΔS 0 were also evaluated.

An organic deposit cleanout job was successfully performed on a horizontal openhole Arab-D reservoir oil well and a high oil rate was restored from the dead well. The well was treated with a proprietary chemical solvent using bullheading and coiled tubing (CT) jetting technique to have maximum coverage of the wellbore from the tubing to long open hole horizontal sections. The treatment performed for this job representedthe first application of this chemical in a carbonate field of North Ghawar. A few wells in this area, lying within the boundary of a gas cap, have experienced asphaltene/paraffin problems that resulted in productivity decline and wellbore inaccessibility. A high gas-oil ratio (GOR) has been thought to be the main reason for asphaltene/paraffin precipitation inside the wellbore and near the formation. Organic depositswere observed to have accumulated in the wellhead and shallow tubing depth. This well was drilled in 2007 on the periphery of the south gas cap of the field and died after being on production for three years at a relative low watercut. The well was reported with a high GOR and water cut around 2% to 3% before dying. Analysis of a downhole sample confirmed 100% hydrocarbon with 81% asphaltic presence. The asphaltene/paraffin deposition was identified as the main reason for the death of this well. Chemical/solvent treatment using a CT jetting/pulsating mechanism was employed to have a maximum benefit. The solvent was proven in the lab to be very effective in dissolving asphaltene/paraffin and had a higher flash point. The job was performed in two stages. In the first stage, about one tubing volume of the solvent was bullheaded and left for soaking for 24 hours. In the second stage, the solvent was placed using 2" CT in the open hole section. This paper describes in detail the nature of the asphaltene problem in this area, the formation mechanism, treatment selection, design and execution, and future prevention approach to avoid recurrence.

We report the results from an investigation of the effects of variations in layer thicknesses during the growth of semiconductor Bragg mirrors on their reflectivity spectra. Different types of variations are investigated and an effort is made to point out the sources of such errors in a typical growth process. It is expected that this study will shed light on the critical control parameters for very highly reflecting mirrors and help the interpretation of the measured spectra from a finished growth run and the identification of the possible sources of deviations from the ideal structure.

Fundamental to successful manufacturing of integrated circuits is the achievement of sufficient control in all process steps to realize, with very high yield, fully functional circuits whose performance and reliability conform to pre-determined standards. Towards this end, it is increasingly necessary to relate in a quantitative manner the sensitivity of the electrical performance of the final devices and circuits to variations in structural parameters and doping profiles, which in turn can be related to process and tool performance variations. In this paper, we describe the results of an analysis performed to quantify the sensitivity of the electrical parameters of a 0.35 /spl mu/m LDD MOSFET to variations in the doping and structural parameters of the device that are anticipated in manufacturing. A central-composite design was used to develop second-order models for six key device electrical parameters. The resulting models are manifested as second-order equations relating the device electrical parameter variations to random variations in seven key device structure and doping parameters. This set of equations thus allows one to understand quantitatively the source and nature of the device electrical parameter variations. A simple Monte Carlo approach is applied to predict the statistical distributions of the key device electrical parameters which result from the random manufacturing variations in the structure and doping parameters by using the quantitative relationships developed in this paper. >

We present room temperature electroabsorption measurements in a Ge/sub 0.2/Si/sub 0.8/ pin photodiode. The results appear to be very similar to those reported earlier on Ge/sub x/Si/sub 1-x//Si multiple quantum wells. >

We report on the design and growth by molecular beam epitaxy of a GaAs/AlAs Bragg mirror with four reflectivity bands. High reflectivity is achieved in all the bands, and there is good agreement between measured and simulated results.

Beyond third generation (B3G) and fourth generation (4G) communication systems require bandwidth efficiency and low complexity receivers to accommodate high data rate and large number of users per cell. This paper provides the recommendations for why interleave division multiple access (IDMA) stands out among all the present day multiple access systems. Even if IDMA is a special case of code division multiple access (CDMA), it simply trounces CDMA as far as the cell capacity is concerned. In IDMA, interleavers are used as the only means for user separation. Interleaver size can be varied for a set of users but the recommended interleaver size is 1024 bits at which it provides better efficiency and minimum processing delay. Investigations carried throughout this paper are while using 1024 bit interleavers. IDMA exhibits the tendency to handle huge number of users.

Interleave Division Multiple Access (IDMA) is one of the competitors for next generation wireless systems. IDMA not only inherits all the advantages of CDMA but also has the capability to overcome its deficiencies. In this paper, security analysis of IDMA system has been carried out through NIST tests and it has been found that it is highly secure on its own, not requiring any additional security device. In other words, IDMA exhibits security features of an efficient crypto system.

Traditionally, mirror design at the wavelengths important for fiber optic systems (1.3 and 1.55 μm) has suffered from the low refractive index step available between InP and its lattice‐matched alloys; the InP/In0.53Ga0.47As combination provides the largest index step, but at λ=1.55 μm absorption in the In0.53Ga0.47As layers degrades reflectivity. We have used the Burstein shift in n+:In0.53Ga0.47As to reduce the band‐to‐band absorption. This has yielded InP/In0.53Ga0.47As Bragg reflectors with reflectivity greater than 97%. These mirrors have been incorporated into a high‐efficiency resonant‐cavity photodetector operating at 1.55 μm.

A new dual‐wavelength, resonant‐cavity photodiode is described. It has previously been shown that the resonant‐cavity structure can achieve high quantum efficiencies in a relatively narrow spectral region with thin absorbing regions. In this letter, a dual wavelength mirror is incorporated into the cavity to achieve operation in two wavelength regions. Peak external quantum efficiencies greater than 50% were demonstrated at 730 and 910 nm.

Aluminium(III) phosphate was observed to have a very high selectivity towards Pb2+ ions. Under similar conditions, the sorption capacities of the exchanger were observed to follow the order: Pb2+ > Zn2+> Ni2+ > Co2+. The potentiometric titration data were used to determine the deprotonation constants (pKa) of AlPO4 which were dependent upon the temperature and nature of the metal cations present in the aqueous phase. Different physico‐chemical methods i.e. FTIR, EPM and the wet chemical analyses were used to investigate the uptake mechanism of Pb2+ by the solid, which showed that no new solid phases were present in the solid residue after sorption of Pb2+ at pH 5. The exchange between protons from the surface and Pb2+ from solutions was found to be responsible for Pb2+sorption by aluminum(III) phosphate.

We report the successful combination of asymmetric and dual mirror designs to fabricate a strained‐layer GeSi/Si Bragg mirror with twin peaks at 632 and 780 nm. The absorption in the GeSi/Si mirror is found to be small and is compensated by the increased refractive index step available at shorter wavelengths. We also propose a dual photodetector that will exhibit high efficiencies at both the resonant wavelengths. The small absorption thickness of this photodetector as compared to conventional silicon photodiodes is expected to result in higher speeds.

Sorption studies were conducted for Co2+ ions on AlPO4 at different concentrations and temperatures. Sorption of Co2+ was found to increase with increase in concentration and temperature. To determine the mechanism of the sorption process, dissolution of AlPO4 in the presence of Co2+ ions and desorption studies were performed which indicated the mechanism of sorption to be the ion exchange followed by precipitation. FTIR studies were also employed to confirm the proposed mechanism.

CMOS technology is being scaled to sub-0.1 /spl mu/m gate length and to power supply (V/sub dd/) of 1.2 V for applications of high density at lower active power than achievable with a 1.5 V-1.8 V CMOS. Many challenges are observed at this technology node including choice of gate dielectric for applications with sub-2.5 nm physical SiO/sub 2/ gate dielectric (or electrical equivalent), and maintaining roadmap performance at 1.2 V, which will require an increase in maximum off current. In this work, the nitrided gate dielectric is formed by Remote-Plasma Nitridation (RPN) of an initial thick and thus, manufacturable, physical SiO/sub 2/ layer /spl sim/3.0 nm, to achieve a final effective physical dielectric thickness /spl les/2.5 nm. In this work, for an effective t/sub ox/(acc)=3.0 nm (corresponding to /spl sim/2.5 nm effective physical Si0/sub 2/ dielectric), nMOS and pMOS nominal I/sub drive/ is 532-55 /spl mu//spl Aring///spl mu/m and 230-240 /spl mu//spl Aring///spl mu/m, respectively, at 1.2 V, with max. I/sub off/=5-10 nA//spl mu/m, With an increase in maximum I/sub off/ from 1 nA//spl mu/m (previous work) to e.g. 5 nA//spl mu/m, the 1.2 V FOM is within 3% of the target figure-of-merit specification. Nonetheless, for scaled 1.2 V technology, the effective physical gate dielectric thickness will be required to be reduced to

A novel replacement gate design with 1.5-3 nm oxide or remote plasma nitrided oxide gate insulators for sub-100 nm Al/TiN or W/TiN metal gate nMOSFETs is demonstrated. The source/drain regions are self-aligned to a poly gate which is later replaced by the metal gate. This allows the temperatures after metal gate definition to be limited to 450/spl deg/C. Compared to pure SiO/sub 2/, the nitrided oxides provide increased capacitance with less penalty in increased gate current. A saturation transconductance (g/sub m/) of 1000 mS/mm is obtained for L/sub gate/=70 nm and t/sub OX/=1.5 nm. Peak cutoff frequency (f/sub T/) of 120 GHz and a low minimum noise figure (NF/sub min/) of 0.5 dB with associated gain of 19 dB are obtained for t/sub OX/=2 nm and L/sub gate/=80 nm.

High performance 0.1 /spl mu/m (physical) gate length CMOS with 30 /spl Aring/ gate dielectric (C-V: gate accumulated at V/sub gb/=-3 V) is demonstrated at 1.0 V-1.5 V. Scaling to 0.1 /spl mu/m L/sub gate/ CMOS is described. At 1.5 V, nMOS strong and nominal I/sub drive/=757 and 700 /spl mu/A//spl mu/m, and pMOS strong and nominal I/sub drive/=337 and 300 /spl mu/A//spl mu/m. For high performance at 1.0 V, n- and pMOS are designed with low V/sub T/ and higher I/sub off/ (100 nA//spl mu/m at L/sub g//sup min/). At 1 V, nMOS strong and nominal I/sub drive/ is 516 and 473 /spl mu/A//spl mu/m; pMOS strong and nominal I/sub drive/ is 220 and 188 /spl mu/A//spl mu/m. Benchmarking to FOM and CV/I metrics is performed for this 1.0-1.5 V, 0.1 /spl mu/m node and prior 1.8-1.5 V, 0.18 /spl mu/m nodes. Present 1.5 V, 0.1 /spl mu/m CMOS (as well as our recently reported 1.8-1.5 V, 0.18 /spl mu/m CMOS) has FOM and CV/I values better than the literature trend. The FOM at V/sub DD/=1.0 V (max I/sub off/=100 nA//spl mu/m) is the same as the 1.5 V FOM (max I/sub off/=1 nA//spl mu/m).

Resonant-cavity photodetectors (RECAPs) can circumvent the tradeoff between quantum efficiency and bandwidth that can limit the performance of conventional photodiode structures. For example, a Si-based RECAP has achieved 65% external quantum efficiency with almost 10x improvement in bandwidth compared to commercially-available Si p-i-n photodiodes. In addition, the wavelength selective spectral response offers potential advantages for applications where filtering is needed such as wavelength division multiplexing (WDM). In this paper, we demonstrate, for the first time, a resonant-cavity, separate absorption and multiplication (SAM) avalanche photodiode (APD). The motivation for using the SAM-APD structure is to achieve single carrier injection into the multiplication region and thus obtain low excess multiplication noise. We also demonstrate a long-wavelength, resonant-cavity photodetector that exhibits a high quantum efficiency and the narrowest spectral-linewidth reported to date.

We have used photocurrent measurements to demonstrate a strong electroabsorption effect in GexSi1−x/Si multiple quantum wells grown by remote plasma‐enhanced chemical vapor deposition. Large voltage‐induced shifts in absorption are observed at room temperature in the wavelength range from 1.2 to 1.58 μm. We anticipate that the results can be extended to fabricate GexSi1−x optoelectronic devices operating at room temperature.

The performance of conventional photodiodes is limited by an intrinsic tradeoff between quantum efficiency and bandwidth. We have successfully demonstrated that resonant-cavity photodiodes can simultaneously achieve high quantum efficiency and wide bandwidths. The resonant-cavity approach increases the absorption through multiple reflections between two parallel mirrors. In addition, the wavelength selective spectral response offers potential advantages for applications where filtering is needed such as wavelength division multiplexing. In this paper, we report on a resonant-cavity, separate absorption and multiplication avalanche photodiode (APD). An avalanche gain of more than 40 has been obtained. The peak external quantum efficiency was measured to be approximately 80% at 890 nm with a spectral response linewidth of less than 7 nm. Without cavity enhancement, the efficiency of these APDs would be less than 5% because the absorbing layer is only 500 angstroms thick. The structure was designed to provide electron injection into the multiplication region because we have determined experimentally that for Al0.4Ga0.6As, the electron ionization coefficient is larger than that of the hole. Based on the conventional formulation for excess noise, the ratio of ionization coefficients is as low as (beta) /(alpha) equals 0.2.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The rapid emergence of high-performance optical systems has accentuated the need for photodiodes with enhanced performance and functionality. In this paper we will describe a new class of photodiodes that utilize novel resonant-cavity structures to achieve high speed, high quantum efficiency, and a narrow spectral response which may prove useful for some wavelength division multiplexing applications. The resonant-cavity photodiode consists of a thin absorbing layer sandwiched between two dielectric mirrors. One advantage of this structure is that it can be utilized to circumvent the responsivity/bandwidth tradeoff inherent to conventional PIN photodiodes structures. For the typical normal-incidence photodiode a wide bandwidth necessitates a thin absorption layer which, in turn, results in low quantum efficiency. The resonant-cavity structure, on the other hand, effectively decouples the responsivity from the transit-time component of the bandwidth because the optical signal makes multiple passes across the thin absorbing layer inside the microcavity. The resonant- cavity approach has been utilized for p-i-n photodiodes, phototransistors, dual-wavelength photodetectors, avalanche photodiodes (APDs), and Schottky barrier photodiodes. In this paper we will concentrate on two specific devices, a Si1-x/Gex resonant-cavity p-i-n photodiode and a resonant-cavity APD with separate absorption and multiplication regions.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A red shift of the fundamental absorption edge due to an electric field applied perpendicular to the multiple quantum wells (MQWs) may result from quantum effects such as the Quantum Confined Stark Effect (QCSE) [1] and has already been demonstrated in several compound semiconductors, e.g. the GaAs/AlGaAs system [2] and the InP/InGaAs system [3]. However, no such room-temperature effects have been reported for the GexSi1-x system although the presence of the QCSE has been indicated and photocurrent measurement results at 77 K have been shown [4]. In this communication we present room temperature photocurrent measurements in GexSi1-x/Si MQWs grown by Remote Plasma-enhanced Chemical Vapor Deposition (RPCVD) [5],[6]. These measurements indicate that optoelectronic devices such as optical modulators [7] and Self Electrooptic Devices (SEEDs) [8] operating at the technologically important wavelengths of 1.3 fim and 1.55 μm can be realized.