Large nonlinear optical effect in an InGaAs/InAlAs multiquantum well waveguide

All-optical refractive nonlinearity in a passive InGaAs/InAlAs multiquantum well waveguide is evaluated for TE and TM modes at 1.55 mu m wavelength and room temperature. A quarter wavelength change in the optical path length is observed at an input pump light power of 6.5 mW for 1.47 mu m wavelength in a 960 mu m long device. Nonlinear refractive index n/sub 2/ is evaluated to be -1.2*10/sup 6/ and -0.5*10-6cm/sup 2//W for the TE and the TM modes, respectively.<>     

Photoconductivity response times of InGaAs/InAlAs multiquantum well waveguide modulators

The pulsed photoconductive response times of 10 and 25 well InGaAs/InAlAs quantum well waveguide modulators are investigated. In both devices comparable sweep-out times for electrons and holes and significant reduction in internal quantum efficiency for fields <200 kV/cm are observed. A dependence on bias voltage and quantum well number is observed which suggests that carrier recapture, or sequential tunnelling, is significant for fields near 70 kV but not for fields >200 kV/cm.<>     

Impact ionization in InAlAs/InGaAs/InAlAs HEMT's

The kink effect and excess gate current in InAlAs/InGaAs/InAlAs HEMT's have been linked to impact ionization in the high field region of the channel. In this letter, a relationship is established between experimentally measured excess gate current and the tunneling of holes from the quantum well formed in the channel. The channel hole current is then obtained as the quotient of the excess gate current to the gate-voltage-dependent transmission probability. This channel hole current follows the exponential dependence of the ionization constant on the inverse electric field     

Ordering in InGaAs/InAlAs layers

The structure of InCaAs/InAlAs layers lattice matched to an InP substrate, grown on either (100) or on (110) with a 4° tilt toward [111] at 500 and 300°C has been investigated by transmission electron microscopy. High perfection resulted for the layers grown on [001] oriented substrates whereas growth on the near [110] substrates resulted in compositional nonuniformities, macrosteps formation, and ordering of the group III elements. This difference in structural perfection between the two sets of samples was also reflected in differences in electrical properties.     

Demonstration of an InGaAsP/InGaAs multiquantum well active-gratingsurface-emitting amplifier

The design and operating characteristics of an InGaAsP/InGaAs strained-layer multiquantum-well active-grating surface-emitting amplifier operating at a wavelength of 1.6 μm are reported. Single-wavelength operation was obtained with 25-dB suppression of amplified spontaneous emission at 150-mW peak power output with a differential quantum efficiency of 24%. This result verifies earlier theoretical predictions that a power output per unit length of ~1 W/cm is feasible     

Delta-doping-enhanced InGaAs/InAlAs heterobarrier diodes

Modification of the effective conduction-band offset in InGaAs/InAlAs isotype heterojunctions by incorporating, during epitaxial growth, a doping dipole formed by alternate n⁺, p⁺ delta (δ-) doping is demonstrated. Greatly improved current rectification is found when the dipole polarity enhances the potential barrier     

Impact ionization in InAlAs/InGaAs HFET's

The presence of an energy barrier to the transfer of holes from the channel to the gate electrode of InAlAs/InGaAs HFET's prevents the gate current from being a reliable indicator of impact ionization. Consequently, we have used a specially designed sidegate structure to demonstrate that due to the narrow bandgap of InGaAs, impact ionization takes place in the channel of these devices under normal operating conditions. The ionization coefficient was found to follow a classic exponential dependence on the inverse electric field at the drain end of the gate, for over three orders of magnitude     

具有优化倍增层InAlAs/InGaAs雪崩光电二极管

通过优化倍增层的厚度,研究了InAlAs/InGaAs雪崩光电二极管增益带宽积和暗电流之间的关系。利用仿真计算得出200 nm厚的倍增层能够改善增益带宽积并降低暗电流。制成的InAlAs/InGaAs 雪崩光电二极管性能优异,与计算趋势一致。在获得0.85 A/W的高响应和155 GHz的增益带宽积的同时,器件暗电流低于19 nA。这项研究对雪崩光电二极管在未来高速传输的应用具有重要意义。     

InP/InAlAs/InGaAs quantum wires

Single InGaAs quantum wires and stacked InGaAs quantum wires with InAIAs barriers have been fabricated on V-grooved InP substrates by low pressure metal-organic chemical vapour deposition (MOCVD). We have found growth conditions where the InAIAs barrier exhibits a resharpening effect, similar to that of AlGaAs utilized for growth on GaAs substrates. The existence of structural and electronic quantum wires in the bottom of the grooves is proven.     

Improved InAlAs/InGaAs HEMT characteristics by inserting an InAslayer into the InGaAs channel

An InAlAs/InGaAs HEMT with a thin InAs layer inserted into the InGaAs channel is proposed and its electron transport properties and device performances have been investigated. By optimizing the thickness and the exact point of insertion in the InAs layer, the mobility and electron velocity at 300 K have been increased by 30% and 15%, respectively, compared to the conventional heterostructure. In addition, a maximum intrinsic transconductance of 970 mS/mm and a maximum current gain cutoff frequency of 58.1 GHz have been attained by a 0.6 μm-gate-length device     

Optical effect in InAlAs/InGaAs/InP MODFET

Analytical results have been presented for an optically illuminated InAlAs/InGaAs/InP MODFET with an opaque gate. Partial depletion of the active region is considered. The excess carriers due to photo generation are obtained by solving the continuity equation. The energy levels are modified due to the generation of carriers. The surface recombination effect has also been taken into account. The results of I-V characteristics have been compared under dark conditions, since under illumination experimental results are not available. The offset voltage, sheet concentration, I-V, and transconductance have been presented and the effect of illumination discussed     

Electron mobility and drift velocity in selectively doped InAlAs/InGaAs/InAlAs heterostructures

An increase in the electron mobility and drift velocity in high electric fields in quantum wells of selectively doped InAlAs/InGaAs/InAsAs heterostructures is obtained experimentally via controlling the composition of semiconductors forming the interface. The electron mobility at the interface in the In_0.8Ga_0.2As/In_0.7Al_0.3As metamorphic structure with a high molar fraction of In (0.7–0.8) is as high as 12.3 × 10³ cm² V⁻¹ s⁻¹ at room temperature. An increase in the electron mobility by a factor of 1.1–1.4 is attained upon the introduction of thin (1–3 nm) InAs layers into a quantum well of selectively doped In_0.53Ga_0.47As/In_0.52Al_0.48As heterostructures. A maximal drift velocity attains 2.5 × 10⁷ cm/s in electric fields of 2–5 kV/cm. The threshold field F _th for the intervalley Γ-L electron transfer (the Gunn effect) in the InGaAs quantum well is higher than in the bulk material by a factor of 2.5–3. The effect of two- to threefold decrease in the threshold field F _th in the InGaAs quantum well is established upon increasing the molar fraction of In in the InAlAs barrier, as well as upon the introduction of thin InAs inserts into the InGaAs quantum well.     

High-field transport in InGaAs/InAlAs modulation-doped heterostructures

The velocity-field and mobility-field characteristics of normal and inverted InGaAs/InAlAs modulation-doped heterostructures grown by molecular-beam epitaxy have been measured at 300 and 77 K. Veloczities of 3.0 × 10⁷and 1.7 × 10⁷cm/s have been measured in the normal and inverted structures, respectively, at 77 K. Current instabilities are observed at the corresponding field values. Hall mobilities decrease With field beyond 500 V/cm, principally due to phonon scattering. The mobilities in normal and inverted heterostructures attain Similar values at fields higher than 1 kV/cm, irrespective of the low-field values.     

High-performance InAlAs/InGaAs HEMTs and MESFETs

The fabrication and microwave performance of heterostructure InAlAs/InGaAs HEMTs (high-electron-mobility transistors) and MESFETs are described. Maximum stable gains of 14.3 dB for a HEMT and 12 dB for a MESFET at 26.5 GHz have been achieved. These are believed to be record gains for FETs having gates as long as 0.7 μm     

应变补偿InGaAs/InAlAs量子级联激光器

利用应变补偿的方法研制出激射波长 λ≈ 3.5— 3.7μm的量子级联激光器 .条宽 2 0 μm,腔长 1 .6mm的 Inx Ga1- x As/Iny Al1- y As量子级联激光器已实现室温准连续激射 .在最大输出功率处的准连续激射可持续 30 min以上 .     

High-speed InAlAs/InGaAs heterojunction bipolar transistors

InAlAs/InGaAs heterojunction bipolar transistors fabricated from wafers grown by molecular beam epitaxy are discussed. A cutoff frequency of 32 GHz for a collector current of 20 mA is achieved in the emitter area of devices 6×10 μm². The use of heavily doped and nondoped InGaAs layers as the emitter cap and collector, respectively, results in a reduction of the emitter and collector charging times; this, in turn, leads to improved microwave performance     

Processing techniques for InGaAs/InAlAs/InGaAs spin field effect transistors

Wet etch processing techniques for InGaAs/InAl/As/InGaAs transistors are used to fabricate an N-channel HEMT (High Electron Mobility Transistor) with Fe contacts. These processing techniques can easily be extended for dilute magnetic semiconductor regrowth and for testing of various spin injection geometries.     

High-performance double-modulation-doped InAlAs/InGaAs/InAs HFETs

We demonstrate the improvement of double-sided-doped InAlAs/InGaAs MODFETs by inserting a thin InAs layer in the center of the conventional InGaAs channel. A maximum extrinsic transconductance of 1.4 S/mm is achieved for 0.13-μm devices. The current gain cutoff frequency of this device is as high as 265 GHz. Delay time analysis shows a significant improvement in the effective saturated velocity, from 2.4×10⁷ cm/s for LM devices to 3.1×10⁷ cm/s for InAs devices. We believe the superior performance of this device is primarily due to the reduction of scattering from donor layers, especially under the channel, and the interface roughness, which is achieved by inserting a 4-nm InAs layer in the channel     

应变补偿InGaAs/InAlAs量子级联激光器

利用应变补偿的方法研制出激射波长λ≈3.5—3.7μm的量子级联激光器.条宽20μm,腔长1.6mm的InxGa1-xAs/InyAl1-yAs量子级联激光器已实现室温准连续激射.在最大输出功率处的准连续激射可持续30min以上.     

InAlAs/InGaAs HBT X-band double-balanced upconverter

We report on an InAlAs/InGaAs HBT Gilbert cell double-balanced mixer which upconverts a 3 GHz IF signal to an RF frequency of 5-12 GHz. The mixer cell achieves a conversion loss of between 0.8 dB and 2.6 dB from 5 to 12 GHz. The LO-RF and IF-RF isolations are better than 30 dB at an LO drive of +5 dBm across the RF band. A pre-distortion circuit is used to increase the linear input power range of the LO port to above +5 dBm. Discrete amplifiers designed for the IF and RF frequency ports make up the complete upconverter architecture which achieves a conversion gain of 40 dB for an RF output bandwidth of 10 GHz. The upconverter chip set fabricated with InAlAs/InGaAs HBT's demonstrates the widest gain-bandwidth performance of a Gilbert cell based upconverter compared to previous GaAs and InP HBT or Si-bipolar IC's