A. Sanz-Hervás

Determination of the pyroelectric coefficient in strained InGaAs/GaAs quantum wells grown on (111)B GaAs substrates

We report an experimental determination of the pyroelectric coefficient for strained InGaAs layers in a pseudomorphic piezoelectric In0.17Ga0.83As/GaAs multiquantum well in a p-i-n diode configuration which was grown on a (111)B GaAs substrate by molecular-beam epitaxy. By analyzing the Franz–Keldysh oscillations in the photoreflectance spectra over the temperature range 11–300 K, we obtained the temperature dependence of the piezoelectric field, from which the temperature variation of the piezoelectric constant e14 was deduced. A linear dependence of e14 with temperature was observed. Therefore, the strain-induced component of the pyroelectric coefficient of (9.3±0.3)×10−7 C/m2 K was determined for this material system.

High quality GaAs/AlGaAs quantum wells grown on (111)A substrates by metalorganic vapor phase epitaxy

Abstract Growth of GaAs and AlGaAs epitaxial layers on both (111)A and (111)13 faces of GaAs substrates was studied by the atmospheric metalorganic vapor phase epitaxy (MOVPE) technique. We show that GaAs and AlGaAs layers with excellent surface quality can be grown at relatively low temperatures and V/III ratios (600°C, 15) on the (111)A face, whereas for layers on the (111)13 face a higher growth temperature (720°C) was required. GaAs/AlGaAs quantum well (QW) structures were successfully grown for the first time on the (111)A GaAs face by the MOVPE technique. The effects of various growth conditions on the surface morphology of the epilayers were studied. For the (111)A surface a wide growth window with temperatures in the range 600°-660°C and V/III ratios varying from 15 to 45 was established for obtaining excellent surface morphology. The properties of the QWs were investigated by high resolution X-ray diffractometry, photoluminenscence and photoreflectance measurements. These measurements indicate that the QWs are of very high structural and optical quality.

Interfacial properties of strained piezoelectric InGaAs∕GaAs quantum wells grown by metalorganic vapor phase epitaxy on (111)AGaAs

In this work we employed photoreflectance spectroscopy over the temperature range 11-300K to investigate the heterointerfaces of a strained piezoelectric InGaAs∕GaAs single quantum well structure grown on a (111)AGaAs substrate by metalorganic vapor phase epitaxy. Photoreflectance spectroscopy measurements in combination with a theoretical analysis using the quantum well structural parameters obtained by high-resolution x-ray diffractometry enabled us to evaluate separately the abruptness and roughness of the quantum well interfaces. The excellent agreement between the experimental and calculated transition energies for a quantum well structure with a well width of 41A and 13% In demonstrates that the heterointerfaces are abrupt. From a theoretical analysis of the temperature dependence of the photoreflectance broadening parameters, based on the Bose-Einstein phonon-coupling model, we determined the longitudinal optical phonon energy and the electron-phonon coupling strength. This analysis shows an interf...

Metalorganic vapor phase epitaxy growth and properties of GaAs/AlGaAs and InGaAs/GaAs quantum well structures on (111)A GaAs substrates

We review the recent advances in the fabrication and properties of GaAs/AlGaAs and InGaAs/GaAs quantum well (QW) structures grown on (111)A GaAs substrates by atmospheric pressure metalorganic vapor phase epitaxy (MOVPE). We show that a 25-period GaAs/AlGaAs multi-QW (MQW) structure was fabricated with good crystal quality, high photoluminescence (PL) emission intensity and monolayer (ML) interfacial roughness. A PL full width at half maximum (FWHM) of 10.5 meV was achieved for a 25-period MQW with a well width of 44 A. This is the narrowest linewidth reported to date for any similar structures grown on (111)A or B substrates by any growth technique. We also report the properties of an InGaAs/GaAs single quantum well structure grown on (111)A GaAs. For this structure, the PL FWHM value was 9.1 meV, corresponding to a 1 ML interfacial roughness for a well width of 41 A. This is the first demonstration of an InGaAs/GaAs quantum well structure grown on (111)A or (111)B GaAs by MOVPE.

Interfacial properties of (111)A GaAs/AlGaAs multiquantum-well structures grown by metalorganic vapor phase epitaxy

We present the heterointerfacial properties of GaAs/AlGaAs multiquantum-well structures grown by atmospheric-pressure metalorganic vapor phase epitaxy on (111)A GaAs substrates at a relatively low growth temperature of 600 °C. For a 25-period GaAs/Al0.27Ga0.73As multiquantum-well structure with a well width of 44 A, a photoluminescence linewidth of 10.5 meV was observed, which is smaller than previously reported for a similar GaAs/AlGaAs multiquantum-well structure grown by molecular beam epitaxy on (111)A GaAs. As this linewidth corresponds to a combined well-width fluctuation and interfacial roughness throughout the 25 periods of at most ±1 monolayer, it is concluded that epitaxial growth on the (111)A surface can result in high-quality heterointerfaces, particularly at low growth temperatures.

Piezoelectric InGaAs/GaAs/AlGaAs quantum well lasers grown on (111)A GaAs by metalorganic vapor phase epitaxy

This presents the properties of semiconductor double confinement strained PE InGaAs/GaAs/AlGaAs QW laser diodes grown on (111)A GaAs by MOVPE. The QW laser were grown on [111]A-oriented GaAs substrates and were extensively analyzed before laser fabrication by photoluminescence, high-resolution X-ray diffractometry, and transmission electron microscopy and was shown that these strained QWs have excellent interfacial properties and are fully strained without any evidence of strain relaxation. The optical and electrical characteristics of these lasers at low temperature and room temperature lasing in the 1.0-1.1/spl mu/m wavelength region were also presented.

Photoreflectance evaluation of MOVPE AlGaAs/GaAs multiple quantum wells on (111)A GaAs

Abstract The Photoreflectance (PR) technique was applied to evaluate a 25-period Al 0.27 Ga 0.73 As/GaAs multiquantum-well (MQW) structure with a well length of 55 A grown by atmospheric pressure metalorganic vapor phase expitaxy (MOVPE) on a (111)A GaAs substrate. Structural parameters such as well and barrier lengths, and the Al fraction in the barriers were accurately determined by high resolution X-ray diffractometry (HRXRD). The PR spectrum exhibits all the possible confined QW transitions between electron and hole sub-bands. The theoretically calculated transition energies are in very close agreement (±1 meV) with those experimentally determined from the PR spectrum even up to the highest possible transition for these wells. From a detailed monolayer (ML) analysis of the various transition energies it is concluded that the QW interfaces have much less than a ±1 ML fluctuation over the 25 periods and that the interfaces are smooth, abrupt and uniform. In addition, photoluminescence (PL) measurements were also used to further assess the optical quality. The PL full width at half maximum (FWHM) is 12.5 meV, which corresponds to less than a ±1 ML fluctuation throughout the 25-period MQW in agreement with the PR analysis. This FWHM is the best value reported to date for AlGaAs/GaAs MQW structures grown on {111} GaAs substrates either by MBE or MOVPE.

Structural and optical properties of very high quality GaAs/AlGaAs multiple quantum well structures grown on (111)A substrates by MOVPE

We report an investigation of the structural and optical properties of the first high quality GaAs/AlGaAs multi-quantum-well structures grown on (111)A substrates by the metallorganic vapor phase epitaxial process at the relatively low temperature of 600/spl deg/C. By high-resolution X-ray diffractometry it is shown that the structure analyzed has a good crystal quality and period reproducibility. The structural and optical properties were also investigated by photoluminescence and photoreflectance spectroscopies. A photoluminescence linewidth of 12.3 meV at 11 K indicates that the well length (105 /spl Aring/) fluctuation over 10 periods is at most /spl plusmn/3 monolayers. A detailed analysis of the photoreflectance spectrum at 11 K permits an excellent identification of all the allowed and also weakly allowed optical transitions expected for this structure, further demonstrating that the heterointerfaces are abrupt and smooth.