Laser emission in HgCdTe in the 2–3.5 μm range

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.

InGaAsP lasers incorporating strained quantum wells have recently shown superior performance in the 1.3 /spl mu/m band. We report both high-power, low RIN lasers and high-speed, low theshold lasers obtained from strained quantum well material. In conclusion, we have demonstrated high-performance 1.3 /spl mu/m lasers obtained from strained quantum well material. Lasers can be optimized for both analog and digital applications.

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

We have developed a high resolution technique for examining minority carrier emission from defect states in semiconductors called Laplace minority carrier transient spectroscopy (LMCTS). The experiment uses the same analytical approach to the capacitance transient as Laplace deep level transient spectroscopy (LDLTS), but minority carriers are injected into the depletion region by application of a suitable light pulse. The combination of LDLTS and LMCTS means that detailed emission properties of closely spaced majority and minority carrier traps across the whole band gap can be now characterized. The technique has been used to study minority carrier traps in gas source molecular beam epitaxy-grown Si/Si0.86Ge0.14 strained quantum wells. Initially the technique was evaluated by comparing LMCTS of a hole trap associated with the gold–hydrogen complex in n-type silicon with LDLTS of the same trap in p-type silicon. Both techniques confirm that this level consists of two states, as previously suggested in the literature. LMCTS was then applied to an n-type multiquantum well Si/SiGe layer. We have been able to measure directly the emission rate of holes out of SiGe quantum wells using LMCTS. The emission rate exhibited only slight temperature dependence, in strong contrast to that of holes which are thermally emitted from isolated point defects. We show that in the particular case of LMCTS, a temperature invariant emission rate out of quantum wells is to be expected, and this is consistent with theoretical predictions.

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.

We present a transmission method to determine the polarization axis fluctuations for VCSEL (Vertical Cavity Surface Emitting Laser). The research is focused mainly on commercial lasers operatingat 780 nm, designed forlaser spectroscopy. The angle fluctuation of the laser linear axis polarization iselaborated to be less than 150 mrad. Measurement errors of this method are studied and calculated. The measurement uncertainty is ?1,4 mrad andthis is equivalent to ? 5? of arc.Changes of the linear polarization axis depending on the laser current and temperaturearepresented. Full Text: PDF References T. Ohtoshi et al., "Dependence of optical gain on crystal orientation in surface?emitting lasers with strained quantum wells", Appl. Phys. Lett.63, 1886 (1994). CrossRef K. Tateno et al., "Growth of vertical-cavity surface-emitting laser structures on GaAs (311)B substrates by metalorganic chemical vapor deposition", Appl. Phys. Lett.70, 3395 (1997). CrossRef O. Tadanaga et al., "An 850-nm InAlGaAs strained quantum-well vertical-cavity surface-emitting laser grown on GaAs (311)B substrate with high-polarization stability", IEEE Photon. Tech. Lett.12, 942 (2000) CrossRef K. Choquette, R. Leibenguth, "Control of vertical-cavity laser polarization with anisotropic transverse cavity geometries", IEEE Photon. Tech. Lett. 6, 40 (1994) CrossRef B. Weigl et al., "High-performance oxide-confined GaAs VCSELs", IEEE J. Sel. Top.Quantum Electron. 3, 409 (1997) CrossRef P. Dowd et al., "Complete polarisation control of GaAs gain-guided top-surface emitting vertical cavity lasers", Electron. Lett. 33, 1315 (1997) CrossRef M. Grabherr et al., "Volume production of polarization controlled single-mode VCSELs", Proc. SPIE,6908, 690803 (2008) CrossRef R. Roy et al., "First-Passage-Time Distributions under the Influence of Quantum Fluctuations in a Laser", Phys. Rev. Lett.45, 1486 (1980) CrossRef J. Martin-Regalado et al., "Polarization switching in vertical-cavity surface emitting lasers observed at constant active region temperature", Appl. Phys. Lett. 70, 3350 (1997) CrossRef M. B. Willemsen et al., "Polarization Switching of a Vertical-Cavity Semiconductor Laser as a Kramers Hopping Problem", Phys. Rev. Lett. 82, 4815 (1999) CrossRef M. B. Willemsen et al., "Anatomy of a Polarization Switch of a Vertical-Cavity Semiconductor Laser", Phys. Rev. Lett. 84, 4337 (2000) CrossRef T. Mukaihara et al., "Excess intensity noise originated from polarization fluctuation in vertical-cavity surface-emitting lasers", IEEE Photon. Technol. Lett. 7, 1113 (1995) CrossRef

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.

A finite superlattice with the embedded quantum well

GaSb/InGaSb strained-layer quantum wells by MOCVD

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

Strain compensation allows the synthesis of infinitely thick heterostructures with many highly strained quantum wells. Design criteria are given for optimized strain and thickness parameters in several device geometries. Strain compensation, using alternating layers of opposite strain, is quantitatively treated using an energy balance analysis. The upper bound to stability for strained multiple quantum wells with and without strain compensation is defined for geometries typically used in optoelectronic devices. Highly metastable structures (composed of many layers of high strain and/or thickness) require low epitaxy temperatures to avoid strain relaxation during growth of individual strained layers, prior to their stabilization in a strain compensated structure.

Optically-pumped nuclear magnetic resonance (OPNMR) spectroscopy is an emerging technique to probe electronic and nuclear spin properties in bulk and quantum well semiconductors. In OPNMR, one uses optical pumping with light to create spin-polarized electrons in a semiconductor. The electron spin can be transferred to the nuclear spin bath through the Fermi contact hyperfine interaction which can then be detected by conventional NMR. The resulting NMR signal can be enhanced four to five orders of magnitude or more over the thermal equilibrium signal. In previous work, we studied OPNMR in bulk GaAs where we investigated the strength of the OPNMR signal as a function of the pump laser frequency. This allowed us to study the spin-split valence band. Here we report on OPNMR studies in GaAs/AlGaAs quantum wells. We focus on theoretical calculations for the average electron spin polarization at different photon energies for different values of external magnetic field in both unstrained and strained quantum wells. Our calculations allow us to identify the Landau level transitions which are responsible for the peaks in the photon energy dependence of the OPNMR signal intensity. The calculations are based on the 8- band Pidgeon-Brown model generalized to include the effects of the quantum confinement potential as well as pseudomorphic strain at the interfaces. Optical properties are calculated within the golden rule approximation. Detailed comparison to experiment allows one to accurately determine valence band spin splitting in the quantum wells including the effects of strain.