Integrated quantum-well-laser transmitter compatible with ion-implanted GaAs integrated circuits

The fabrication of an integrated optoelectronic transmitter consisting of an MOCVD-grown quantum-well laser and ion-implanted metal-semiconductor field-effect transistors (MESFETs) is described. The transmitter is characterised by a laser threshold current of 30 mA, differential quantum efficiency of 50%, MESFET transconductance of 60 mS/mm, and operation at frequencies up to 2 GHz.     

Large Stark shift of the interband transition in two-step quantumwells

Large and near-linear Stark shifts of the electron-heavy-hole ground state excitonic transition were observed in photoluminescence (PL) measurements for a two-step quantum-well (TSQW) structure. The Stark shift was 40 meV while a corresponding square well shifted only 20 meV at a field of 70 kV/cm. The observed Stark shifts agreed well with calculations. The large Stark shift of the TSQW was achieved on a global-to-local state transition realized via tailor-made quantum well (QW) parameters. This structure is an ideal candidate for optoelectronic devices based on the quantum confined Stark effect (QCSE)     

Quantum-well heterostructure lasers

The various features peculiar to the operation of quantum-well semiconductor lasers are described and illustrated with data on single- and multiple-quantum-well AlxGa1-xAs-GaAs heterostructures grown by metalorganic chemical vapor deposition (MO-CVD). Photo-pumped and p-n diode lasers (injection lasers) are described that are capable of continuous room temperature (CW 300 K) operation. The basic problems of carrier collection, thermalization, and quantum-well band filling are considered and have made clear the limits on single quantum-well laser operation and how these can be overcome with multiple quantum-well active regions. The idea that the steplike density-of-states of a quantum-well heterostructure can improve the operation of a semiconductor laser is shown to be valid. Also, it is shown that phonon participation in the operation of a quantum-well laser, which was not anticipated, is a major (even dominant) effect, with perhaps the phonon emission itself in the compact active region being stimulated. Besides the obvious freedom that quantum-well layers offer in how the active region of a semiconductor laser can be designed, quantum-well lasers are shown to exhibit a lesser sensitivity of the threshold current density on temperature, which is explained in terms of the step-like density-of-states and the disturbed electron and phonon distributions in the quantum-well active regions. Values as high assim437degC have been obtained for T0in the usual expressionJ_{th}(T) = J_{th}(0) exp (T/T_{0}). Since photopumped multiple-quantum-well MO-CVD AlxGa1-xAs-GaAs heterostructures have operated as CW 300 K lasers with only 5-10 mW of photoexcitation (uncorrected for focusing and window losses,lambda sim 5145Å), it is suggested that quantum-well laser diodes can be made that will operate at ∼1 mA or even less excitation.     

An over 10-Gb/s transmission experiment using a p-type delta-dopedInGaAs-GaAs quantum-well vertical-cavity surface-emitting laser

We have fabricated a p-type delta-doped InGaAs-GaAs quantum-well (QW) vertical-cavity surface-emitting laser (VCSEL) with a low-resistance GaAs-AlAs distributed Bragg reflector (DBR). The threshold was as low as 700 μA for 10×10 μm² devices. A penalty-free 10-Gb/s transmission experiment with a 100-m-long multimode fiber was performed using fabricated VCSELs. The modulation speed was up to 12 Gb/s, which was limited by an RC constant. Further threshold reduction and high-speed operation can be expected by controlling the doping concentration in p-type delta-doped layers     

2.0-/spl mu/m single-mode operation of InGaAs-InGaAsP distributed-feedback buried-heterostructure quantum-well lasers

Distributed-feedback (DFB) buried-heterostructure (BH) lasers with quantum-well active region emitting at 2.0 /spl mu/m have been fabricated and characterized. The lasers with four wells showed performance of practical use: threshold current as low as 15 mA for 600-/spl mu/m-long devices and CW single-mode output up to 5 mW at 2.03 /spl mu/m under operation current of 100 mA were observed. The current- and temperature-tuning rates of DFB mode wavelength are 0.004 nm/mA and 0.125 nm/K, respectively.     

Growth and characterization of continuously graded index separateconfinement heterostructure (GRIN-SCH) InGaAs-InP long wavelengthstrained layer quantum-well lasers by metalorganic vapor phase epitaxy

A report is presented on the growth and characterization of the first InGaAs-InP-based graded-index separate-confinement-heterostructure (GRIN-SCH) strained quantum-well lasers operating near 1.47 μm. The structure features linearly graded InGaAsP waveguide layers for both optical and carrier confinement in a very narrow, strained quantum-well layers. The excellent structural quality of the active and waveguide regions has been confirmed by transmission electron microscopy (TEM) and secondary ion mass spectroscopy (SIMS) analysis results. Strained quantum-well lasers with well widths as narrow as 5-6 nm were fabricated with threshold current densities as low as 750 A/cm². Buried-heterostructure lasers based on strained quantum-well active lasers exhibit threshold currents as low as 10-15 mA with quantum efficiency of 70-80%. With antireflection coating on one side of the sample, the laser shows threshold current of 35 mA with highest output power of 160 mW     

Impact of well coupling on the spontaneous emission properties ofGaAs/AlGaAs multiple-quantum-well structures

The impact of well coupling on the emission spectra of multiquantum-well structures is discussed. Luminescence experiments are performed in the temperature range between 1.5 K and room temperature and at various excitation densities. High-excitation room temperature results are used for the calculation of gain profiles. With increasing coupling strength a transition from two-dimensional to three-dimensional behavior of the charge carriers is observed. In particular the two-dimensional gap is lowered, the light-hole-heavy-hole splitting is reduced, the influence of interface roughness on the line shapes is reduced, excitons cease to dominate the room-temperature luminescence, and the low-temperature recombination process switches from a non-k -conserving to a k-conserving one. Some of the fundamental advantages of quantum-well lasers, such as the improved TE/TM mode selection, the small spontaneous-to-stimulated emission ratio, and the tendency towards single-longitudinal-mode operation, are gradually lost. A detailed theory of electronic states in superlattices and of superlattice emission line shapes quantitatively explains these results     

Comparison of heterostructure-emitter bipolar transistors (HEBTs) with InGaAs/GaAs superlattice and quantum-well base structures

The characteristics of InGaP/GaAs heterostructure-emitter bipolar transistors (HEBTs) including conventional GaAs bulk base, InGaAs/GaAs superlattice-base, and InGaAs quantum-well base structures are presented and compared by two-dimensional simulation analysis. Among of the devices, the superlattice-base device exhibits a highest collector current, a highest current gain and a lowest base–emitter turn-on voltage attributed to the increased charge storage of minority carriers in the InGaAs/GaAs superlattice-base region by tunneling behavior. The relatively low turn-on voltage can reduce the operating voltage and collector–emitter offset voltage for low power consumption in circuit applications. However, as to the quantum-well base device, the electrons injecting into the InGaAs well are blocked by the p⁺-GaAs bulk base and it causes a great quantity of electron storage within the small energy-gap n-type GaAs emitter layer, which significantly increases the base recombination current as well as degrades the collector current and current gain.     

Low threshold, room temperature laser diode pumped Sb-based VECSEL emitting around 2.1 /spl mu/m

The operation of a diode-pumped AlGaAsSb/GaInAsSb type-I quantum-well vertical external cavity surface emitting laser (VECSEL) emitting near 2.1 /spl mu/m is reported. The epitaxial structure, grown on GaSb by molecular beam epitaxy consists of a GaSb/AlAsSb Bragg reflector and a GaInAsSb/AlGaAsSb active region. A TEM/sub 00/ low-divergence laser operation is demonstrated in quasi-CW (10 /spl mu/s pulses, 10% duty cycle) from 250 up to 350 K. A threshold as low as 390 W/cm/sup 2/ at 250 K combined with a T/sub 0/ around 33 K has been measured.     

Batch fabrication and structure of integrated GaAs-AlxGa1-xAs field-effect transistor-self-electro-optic effectdevices (FET-SEED's)

The authors have demonstrated a smart pixel prototype field-effect-transistor-self-electrooptic-effect-device (FET-SEED) integrated optoelectronic amplifier utilizing process technology suitable for flexible design and fabrication of high-yield optoelectronic circuits. A single MBE growth sequence provides for quantum-well modulators, photodiodes, doped channel MIS-like field-effect transistors (DMTs), and resistors. The device dimensions are controlled in a planar technology using ion implantation and selective plasma etching for isolation and contacting. Results demonstrate optical amplification in a fully integrated circuit. This technology will enable increased functionality by providing digital electronic processing between optical input and output     

A vertical-cavity surface-emitting laser appliqued to a 0.8-/spl mu/m NMOS driver

An optoelectronic integrated circuit (OEIC) composed of a vertical-cavity surface-emitting laser (VCSEL) appliqued to an NMOS drive circuit was fabricated to form an optical link from the CMOS chip. A custom NMOS circuit was designed and fabricated through the MOSIS foundry service in a standard 0.8-/spl mu/m CMOS process. InGaAs quantum-well VCSELs were grown, fabricated and tested on an n-type GaAs substrate. Next, the VCSELs underwent a substrate removal technique and were appliqued to the NMOS circuitry. The OEIC was tested at the chip level and showed an electrical to optical conversion efficiency of 1.09 mW/V. Modulation results are also discussed.     

Energy Loss Mechanism in Organic and Inorganic Light-Emitting Diodes

We report that there exists a similar energy loss mechanism in fluorescent/phosphorescent organic light-emitting diodes (F/P OLEDs) and inorganic semiconductor optoelectronic devices [1310-nm InGaAsP-InP superluminescent diodes (SLDs)]. The loss of energy in inorganic SLDs based on thickness-altered asymmetric multiple quantum-well (QW) structures occurs depending sensitively on the sequence of QWs, an analogous behavior also observed in F/P OLEDs depending on the sequence of phosphorescent dopants for different colors. It is shown that such an energy (power) loss is evitable by placing long-wavelength QWs near the p-side in inorganic SLDs and similarly long-wavelength phosphors near the hole-transporting layer in F/P OLEDs.     

Very low threshold current densities (under 100 A/cm2) in AlGaAs/GaAs single-quantum-well GRINSCH lasers grown by molecular beam epitaxy

Threshold current densities as low as 80 A/cm2 for 3.3 mm-long cavity lasers, and 93 A/cm2 for 520 ?m-long cavity lasers have been obtained in AlGaAs/GaAs graded-index separate-confinement heterostructure (GRINSCH) single-quantum-well lasers with quantum-well widths between 65?165 A grown by molecular beam epitaxy. The structures were prepared on (100) GaAs substrates and do not display the earlier reported dependence of lasing threshold characteristics on the quantum-well thickness in the range studied (65?165 A).     

Design and Fabrication of 1.25-Gb/s Full-Triplex Transceiver Module With PLC on a Lossy Si Substrate for G/E-PONs

1.25 Gb/s optoelectronic full-triplex transceiver module with planar-lightwave-circuits was designed and fabricated for the fiber-to-the-home services according to G/E-PONs standards. A low electrical crosstalk of the critical characteristics for the reliable operation of the 1.25 Gb/s full-triplex transceiver module is intensively investigated because the electrical crosstalk on a resistive silicon substrate is more serious than that on a dielectric substrate. It is observed that the performances of the transmitter and receiver satisfy the transmitter and receiver specifications defined in the standards. From this proposed module layout, a design convenience as well as a great reduction of the silicon substrate size by about 50% was completely achieved. Consequently, the 1.25 Gb/s full-triplex transceiver module was fabricated with electrical and mechanical packaging technologies such of a low crosstalk design and a passive alignment method.     

Dynamical simulation of quantum-well structures

For the design and development of optical semiconductor devices based on quantum-well structures, the investigation of saturation phenomena is necessary for high optical power operation. By applying stationary physical models, nonlinear effects cannot be described adequately; hence, transient models are important for an accurate analysis. By utilizing transient models, saturation phenomena, signal delays, and distortions can be investigated. For the analysis of integrated optoelectronic devices, such as lasers and modulators, transient transport or density matrix equations for carriers and photons and the Poisson equation have to be solved self-consistently. A transient model which is useful for the investigation of a wide range of optoelectronic applications is presented. Quantum optical phenomena are included by applying the interband density matrix formalism in real-space representation, where the Coulomb singularity is treated exactly in the limits of the discretization. As we focus on electroabsorption modulators, a drift-diffusion model adequately approximates the transport properties. Here, quantum effects are considered by a quantum correction, the Bohm potential. The model is applied to investigate transport effects in InP-based waveguide electroabsorption modulators including strained lattices     

太赫兹量子阱光探测器电子输运特性的MC模拟

半导体器件的MC(蒙特卡罗)模拟是深入研究小尺寸器件的物理过程中必不可少的工具.设计了一种基于三能带近似模型的MC平台,用来研究太赫兹场作用下GaAs/Al0.03Ga0.97As量子阱光探测器内部电子的输运特性.在这个平台的基础上,很好地研究了太赫兹作用下量子阱光探测器在低温和低电场时的电子输运特性.     

几种新型的光电器件

描述用ＳＯＩ技术制造的光耦合ＭＯＳ继电器和多量子阱长波和红外探测器，以及集成异质结晶体管和激光二管于一体的高增益，高灵敏的光电子开关器件，文中着重介绍这些器件的结构，制造工和器件特性，并对其进行了讨论。     

Functional AlGaAs/GaAs heterostructure-emitter bipolar transistor with a pseudomorphic InGaAs/GaAs quantum-well base

A new functional AlGaAs/GaAs heterostructure-emitter bipolar transistor (HEBT) with a pseudomorphic InGaAs/GaAs quantum-well (QW) base structure is presented. Due to the insertion of an InGaAs QW between the emitter–base (E–B) junction, the valence band discontinuity can be enhanced. The excellent transistor characteristics including a high current gain of 280 and a low offset voltage of 100 mV are obtained. In addition, an interesting multiple S-shaped negative differential resistance (NDR) phenomenon is observed under the inverted operation mode. This may be attributed to an avalanche multiplication and sequential two-stage barrier lowering effect.     

Semiconductor optical amplifier for CWDM operating over 1540-1620 nm

A semiconductor optical amplifier was developed for coarse wavelength-division-multiplexing (CWDM) operating over 1540-1620 nm (C-L band). A unique quantum-well structure was designed to meet the requirements for the CWDM operation such as wide bandwidth, low polarization-dependent gain, and high-saturation power at the short wavelength end of the band (1540 nm). Over the band, 24-dB maximum chip gain was obtained with less than 4.3-dB gain flatness and more than 14.6-dBm saturation power.     

Single-interface and quantum-well heterostructure MISFETs

The physical operation of heterostructure metal-insulator-semiconductor field-effect transistors (H-MISFETs) is described and compared with that of more familiar heterostructure FETs. Undoped, doped-channel, and quantum-well MISFETs based on AlGaAs-GaAs heterostructures are examined. The focus is on quantum-well MISFETs, which differ most from more conventional devices. Results are presented of experiments and simulations carried out to study the physical mechanisms related to charge control, gate leakage, device geometry, short-channel effects, buffer leakage, and electron trapping in the devices, and the advantages of other III-V materials systems are described. The potential advantages of H-MISFETs are discussed in terms of particular circuit applications