High-performance 1.3 μm lasers for analog and digital applications

A detailed discussion is given for the x-ray rocking curve analysis of semiconductor heterointerfaces and strained quantum wells using x-ray interferometry. It is shown that for a single beteroepitaxial layer sample and a multiple quantum well sample, the heterointerface where the composition changes in both anion and cation sublattices can be studied with a half monolayer sensitivity by analyzing the x-ray rocking curve profile. Such sample systems include GaInAs/InP, InGaSb, GaInP/GaAs, ZnSe/GaAs, etc. A simple kinematical diffraction principle involved in the x-ray analysis is explained. Namely, the relative phase difference between the reflection amplitudes of any two layers depends on the total sum of strain (or mismatch)-thickness products over the intervening layers and interfaces. The x-ray interferometry is also effective in measuring the strain-thickness product of strained quantum wells. Experimental data and analysis results are presented for a series of functional device structures having a strained quantum well. For a more complicated sample structure which involves both a (strained) quantum-effect layer and gained interfaces, it is shown that the x-ray interferometry is only capable of providing the total strain-thickness product over the quantum layer and the surrounding interfaces, but no detailed information about the interface grading can be gained frommore » the rocking curve analysis alone if only one isolated sample is measured. An experimental data of such a sample, 0.3{mu}m-GaAs/100{Angstrom}-GaInP/GaAs(001), is analyzed. 15 refs., 6 figs.« less

The fabrication of long-wavelength optoelectronic devices on GaAs substrates is an attractive method for monolithic integration of optical and electronic devices on a single chip for applications in telecommunications. In this letter we describe our studies of one such scheme using a novel structure for spatially separating a portion of the biaxial compressive stress due to lattice mismatch of the layers from the well layer, and demonstrate its feasibility. High quality pseudomorphic strained InGaAs quantum wells were grown on GaAs substrates by molecular beam epitaxy with a band edge between 1.3 and 1.4 μm at room temperature. Low-temperature photoluminescence spectroscopy as well as polarization-dependent absorption measurements in a waveguide geometry was used to characterize the structures.

Damage introduced from sputtering deposition, electron-beam evaporation, and thermal evaporation were investigated with an InGaAs/GaAs strained quantum well structure. This strained quantum well structure was found to be a more sensitive probe of damage, revealing metallization-induced damage where none was found using comparable lattice-matched quantum wells. The damage was found to vary with deposition method, deposition rates, or even different metal sources used. Noticeable degradation of the photoluminescence of the strained quantum well was observed after a thin layer (∼100 Å) of metal was deposited.

Thresholdless Auger recombination in InAlAsSb strained quantum wells is studied theoretically. Analytical formulas for the Auger transition matrix element have been derived in the framework of the Kane model. A detailed analysis of overlap integrals between initial and final states of carriers has shown that the strain and light–heavy hole mixing affect both qualitatively and quantitatively the overlap integral between the electron and hole states. The Auger recombination coefficient is found to have a strong dependence on strain, quantum well width and emission wavelength, but weak dependence on temperature. The Auger coefficient temperature dependence is shown to be very sensitive to the bandgap variation with temperature.

Laser emission in HgCdTe in the 2–3.5 μm range

Interface roughness correlation in CdTe/CdZnTe strained quantum wells

Photoluminescence investigation on growth mode changeover in Ge-rich Si 1− xGe x/Si strained quantum wells

GaSb/InGaSb strained-layer quantum wells by MOCVD

This article investigates and improves optical properties of slow light devices. The device structure consists GaAs/AlGaAs [110] strained quantum wells (QWs) based on V-type electromagnetically induced transparency (EIT). In this paper, we use an analytical model in fractional dimension in order to simulate and analysis slow light device. Effects of well width variation have been investigated on exciton oscillator strength (EOS) and fractional dimension parameter. Influences of these parameters alterations have been illustrated in optical properties of slow light system such as slow down factor (SDF) and central energy of the device. Based on obtained results, we can adjust optical variables of slow light system with controlling the well thickness. Using proposed method, we have also estimated the maximum value of SDF about 9×103.

In-plane optical anisotropy was calculated for InGaAs strained quantum wells (QWs) with finite barrier potential on high-index (11n)-oriented GaAs substrates. The mixing effects of the spin–orbit split-off (SO) band were included by using 6 ×6 Hamiltonian based on the Luttinger–Kohn model. Calculated results reveal that optical anisotropy of the narrow QW is strongly dependent on barrier potential height, because the SO band mixing is enhanced by the strong confinement. Substrate off-angle dependence of photoluminescence intensity anisotropy observed in the (11n)A (n = 3, 4, and 5) In0.08Ga0.92As/GaAs strained QWs is well explained by the calculated curve with taking into account of the SO band mixing.

Influence of substrate misorientation on the optical and structural properties of InGaAs/GaAs single strained quantum wells grown on (111)B GaAs by molecular beam epitaxy

We have recently reported optically-pumped lasing in an InGaP/InAlGaP strained quantum well visible vertical cavity surface emitting laser (VCSEL) with both AlAs/AlGaAs distributed Bragg reflectors (DBRs)~ and with InAlPDnAlGaP DBRs2. We have also studied the critical issues for electrical injection in these promising devices and now report the demonstration of the first visible VCSEL diodes. At room temperature with pulsed excitation, the devices lase in a single longitudinal mode within 639.1 nm to 660.7 nm, depending on wafer position. The structures were grown by metalorganic vapor-phase epitaxy (MOVPE) on GaAs substrates and consist of an InAlGaP optical cavity active region surrounded by AlGaAs DBRs. The bottom Si-doped DBR consists of 55.5 periods of alternating AlAs and Al,Gal-,As (x = 0.5) quarter-wave layers with x = 0.75 barrier reduction layers at each interface to reduce series resistance. An identical 36 period C-doped top coupling DBR is used and includes a (p+) GaAs metal contact layer. The InAlGaP optical cavity contains three In0.56Gao.& strained quantum wells in a step graded-barrier separate confinement configuration. Device injection efficiency was optimized by studying the performance of edge-emitting lasers with InAlGaP active regions and AlGaAs DBR cladding layers. Gain-guided etched post test devices were fabricated. A top annulus contact defines emitting diameters of 10 pm and 20 pm with a 5 pm radial thickness, thus, a large percentage of the injected current does not directly contribute to lasing but to device heating. Despite this, lasing wavelengths from 639.1 nm to 660.7 nm were measured, on unrotated wafers, at room temperature without heat-sinking. The pulsed excitation was - 100 ns pulses at 10 kHz to IMHz. Many devices continued lasing with up to a 40% duty cycle at 1MHz. The larger devices typically have a threshold of 30 mA at 2.7 V. The peak output power is 3.38 mW with a resistance of less than 15 0. Substantially improved performance is expected with more sophisticated device processing techniques. This is the first demonstration of InAlGaP visible VCSEL diodes. This work opens the door for advanced device applications such as plastic fiber communications, arrays for displays, interconnects, and holographic memory, and some scanning applications in place of HeNe lasers.

Exciton energy broadening due to interface fluctuations in ZnSe/ZnS xSe 1− x strained quantum wells

The effect of gallium implantation on the intermixing of InGaAs/GaAs strained quantum wells

We report electrical transport data for holes in single strained quantum well structures of the type GaAs/InxGa1−xAs/GaAs with x≊0.2. With modulation doping, 4 K mobilities of ∼3×104 cm2/V s have been achieved. This value is near that attained for electrons in comparable structures, illustrating the enhanced transport possible due to the strain-induced light-hole planar mass.