B.W. Kim

Effect of the growth parameters on the luminescence properties of high-quality GaAs/AlGaAs multiquantum wells on (1 1 1)A substrates by metal organic vapor phase epitaxy

Abstract We report on a study of the growth parameters and their effect on the structural and optical properties of GaAs/AlGaAs multiquantum well (MQW) structures grown on novel (1xa01xa01)A-oriented GaAs substrates by atmospheric-pressure metalorganic vapor-phase epitaxy. The MQW structures have 25 periods with well widths ranging from 25 to 45xa0A and an Al fraction in the barriers of around 25% and were grown at 600°C using V/III ratios ranging from 52 to 261 and various growth rates on exact and misoriented (1xa01xa01)A substrates. High-resolution X-ray diffractometry was used to assess the crystal quality and obtain structural information. The growth rates for GaAs on (1xa01xa01)A and (1xa00xa00) oriented substrates are compared. The optical quality was evaluated by low-temperature photoluminescence (PL) spectroscopy. We determined the optimum growth conditions to obtain high structural quality and PL emission intensity. A PL line width of 10.5xa0meV was achieved, which is the lowest value reported to date for GaAs/AlGaAs MQWs on (1xa01xa01)A or (1xa01xa01)B GaAs by any growth technique, corresponding to less than a ±1 monolayer fluctuation of the well width over the 25 periods.

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 600u200a°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.

MOVPE growth of highly-strained piezoelectric InGaAs/GaAs quantum wells on [111]A-oriented substrates

Abstract In this paper we present a study on the MOVPE growth and optical evaluation of strained InGaAs/GaAs quantum well (QW) structures with In contents of 17% and 22% on [1xa01xa01]A-oriented GaAs substrates. QW structures grown under different growth conditions were extensively analyzed by means of Photoluminescence (PL) spectroscopy. The dependence of the PL intensity and linewidth on the growth temperature and In content are investigated and compared to simultaneously grown [1xa00xa00]-oriented structures. It is shown that excellent QW interfaces with only ±(1–2) monolayer roughness were achieved for the [1xa01xa01]A-oriented structures with 17% In using a wide range of growth temperatures (550–670°C), whereas the interfacial properties of the [1xa00xa00] samples significantly degraded as the growth temperature was increased. For a [1xa01xa01]A QW structure with 22% In the PL characteristics are similar to those obtained for the 17% In sample; on the contrary, for the companion [1xa00xa00] sample a strong degradation of its optical properties is observed.

Structural properties of strained piezoelectric [1 1 1]A-oriented InGaAs/GaAs quantum well structures grown by MOVPE

Abstract We report the structural properties of strained InGaAs/GaAs double confinement quantum well (QW) structures grown on (1xa01xa01)A GaAs by metalorganic vapor phase epitaxy. The structures were extensively analyzed by photoluminescence (PL) spectroscopy, High-resolution X-ray diffractometry (HRXRD) and transmission electron microscopy (TEM). Excellent interfacial characteristics and uniformly strained structures with no compositional modulation were obtained for [1xa01xa01]A-oriented QWs with well widths of 65–100xa0A containing up to ∼20% In grown over a range of growth temperatures and V/III ratios. HRXRD analyses also show that the InGaAs well layers are pseudomorphic. A narrow PL full-width-at-half-maximum (FWHM) of 7xa0meV at 12xa0K was achieved for a QW structure grown at 630°C with a V/III ratio of 260. A monolayer (ML) analysis of PL FWHM data indicates a well width fluctuation of ±1xa0ML, which is consistent with TEM observations showing a well width fluctuation of less than ±2xa0ML. The well width fluctuation values of [1xa01xa01]A QWs are in the range of ±(1–2) ML for growth temperatures of 630°C and 680°C with V/III ratios between 105 and 260, while for simultaneously grown [1xa00xa00]-oriented structures the fluctuations are in the range ±2 to over ±4 ML, depending on the V/III ratio.

MOVPE growth and properties of P-I-N InGaAs/GaAs strained multi-quantum well structures on (1 1 1)A GaAs substrates

Abstract In this paper we present the achievement of high-quality strained InGaAs/GaAs piezoelectric quantum wells embedded in a P-I-N structure which was grown on a (1xa01xa01)A GaAs substrate at a single temperature by atmospheric pressure metalorganic vapor-phase epitaxy. The growth conditions and the structural and optical properties of a 10-period multi-quantum well structure with an In content of 13% in the wells are presented. High-resolution X-ray diffractometry studies show good crystalline and interfacial quality, as well as good repeatability of the quantum well parameters. A photoluminescence full-width at half-maximum value of 11xa0meV at 12xa0K was determined for the principal quantum well interband transition. A monolayer analysis of the principal optical transition, which includes the piezoelectric field, indicates a well width fluctuation of less than ±1 monolayer over the 10 quantum well periods.

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.