Magneto-optical studies of the correlation between interface microroughness parameters and the photoluminescence line shape inGaAs/Ga0.7Al0.3

Abstract

In this work we analyze the relation between the interface microroughness and the full width at half maximum ͑FWHM͒ of the photoluminescence ͑PL͒ spectra for a GaAs/Ga 0.7 Al 0.3 As multiple quantum well ͑QW͒ system. We show that, in spite of the complex correlation between the microscopic interface-defects parameters and the QW optical properties, the Singh and Bajaj model ͓Appl. Phys. Lett. 44, 805 ͑1984͔͒ provides a good quantitative description of the excitonic PL-FWHM. ͓S0163-1829͑99͒01424-1͔The interfaces structural properties in quantum wells ͑QW's͒ have been extensively investigated, as they are extremely important for the high performance of the electronic and optoelectronic QW-based devices. [1][2][3] Semiconductor heterostructures interfaces have been investigated by means of direct or indirect characterization techniques. Direct investigations of the interfacial quality have been obtained, for instance, by scanning tunneling microscopy, atomic force microscopy, and transmission electron microscopy ͑TEM͒. 4 However, interfaces that are deep inside a semiconductor heterostructure are not accessible through direct investigation methods, so optical techniques ͑which indirectly probe the interfaces͒ have been intensively used in semiconductor-interface characterization in QW systems.One of the most efficient sensors used in the optical characterization of interfacial quality, due to their sensitivity to the structural aspects of the interface on the atomic scale, is the behavior of confined excitons. 5 In fact, an interesting subject of debate is the correlation between the excitonic optical properties and the microscopic configurations of the interfaces. [6][7][8] The flat island model ͑FIM͒ associates the properties of the QW emission lines with the microscopic patterns of the interfaces. According to this model, when the excitons are confined in extensive and plane islands, which have larger dimensions than the exciton lateral dimension, the photoluminescence ͑PL͒ emission line splits. These splittings are due to different confinement potentials, which are associated with islands of different sizes. Moreover, each one of the split PL emission line is broadened due to confinementpotential fluctuations. These fluctuations are due to interface microroughness ͑defects with smaller extension than that of the lateral dimension of the confined exciton͒ and to alloy fluctuations, resulting in an inhomogeneous ͑Gaussian͒ broadening of the PL spectrum. In addition, the emission spectra are also broadened due to final-state interactions ͑Lorentzian broadening͒ and due to the thermal distribution of the carriers.In the FIM, the QW has different widths that differ from each other by an integer multiple of monolayers ͑ML͒, resulting in several PL peaks with corresponding differences in energy. However, more recently, splittings in the PL spectra related to noninteger ML variations in the QW width were observed. 9 The authors of Ref. 9 argued that for a realistic description of the interfaces it is necessary to use a...

Monolithic growth of GaAs/Al0.3Ga0.7As multiple quantum well structure on Ge substrate with low defects: theoretical and experimental correlation of the structural and optical properties

“…FWHM of the QWs of both samples are mentioned in table 1. The broadening of PL spectra may occur due to various factors, as mentioned below [24][25][26][27]: The FWHM values monotonically increased with decrease in QW thickness, indicating the microroughness and fluctuation in the Al-composition of the barrier layer near the GaAs/Al x Ga 1-x As interface [28]. Therefore, the variation in experimental FWHM values in the MQW structure of the current study has a strong correlation with the above mentioned expression.…”

Effect of carrier confinement on effective mass of excitons and estimation of ultralow disorder in Al x Ga1−x As/GaAs quantum wells by magneto-photoluminescence

“…and Oliveira et al . had pre-assumed that the fluctuation ( δ 1 ) in the width of QWs as one monolayer thickness, and subsequently they have estimated the lateral inhomogeneities at the hetero-junction of the QWs 17 , 18 . Bansal et al .…”

Heterodimensional charge-carrier confinement in stacked submonolayer InAs in GaAs

“…We now turn our attention to its dependence on B, as shown in argument is that this leads to a reduced disorder averaging and hence an increase in the linewidth [22]. This is based upon the assumption that the correlation length χ 1 of the disorder potential is much smaller than a B .…”