Determination of Optical Properties of the Micro-Facetted InGaAs Quantum Wells and Quantum Wires Using Magnetophotolumin
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ABSTRACT We report optical properties of the micro-facetted InGaAs quantum wells and quantum wires on non-planar substrates employing magnetophotoluminescence (MPL). The InGaAs/GaAs structures were grown by chemical beam epitaxy on V-groove patterned GaAs substrates. In the presence of a magnetic field of 18 T, the diamagnetic shifts of exciton ground states of the (001)and side-QWLs are AE =15.6 and 10.3 meV, respectively. In MPL of the facetted microstructure, we found that the different diamagnetic shifts strongly depend on the magnitude of the effective magnetic field as well as the quantum confinement. From comparing the intensities and full widths at half maximum, we easily found that side-QWLs are of higher quality than (00 1)-QWLs. We also fabricated InGaAs/GaAs quantum wires with a size of about 200 A x (500-600) A. By fitting the diamagnetic shifts (AE =-9.5 meV) of the exciton ground state with the calculated results of a variational method, we estimated that the reduced mass of the exciton is approximately 0.052 mn.
1. INTRODUCTION The use of non-planar substrates has recently drawn a great deal of attention for the possibility of obtaining quantum well (QWL), quantum wire (QWR) and quantum dot (QD) structures having very smooth interfaces and better optical and electrical properties [1, 2]. The reduced dimensionality is expected to improve many physical properties of semiconductors and semiconductor base devices such as high performance devices [3] and opto-electronic and photonic devices of lasers [4] and waveguides [5]. On the other hand, epitaxial growth on non-(001)-oriented planar substrates which are far from (001) substrates has been tried for superior properties such as low threshold current, low compensation and better surface morphology [2, 6-8]. In the case of (I 11) substrates, a higher peak-to-valley current ratio in resonant tunneling devices and a higher luminescence intensity than (001) substrates have been reported [9, 10]. To achieve better crystal growth properties, (113) substrates have been used. The ideal (113) surface is non-polar with equal densities of single and double dangling bonds, i.e., an equal number of steps and terraces, and this is an average of the (001) and (111) surfaces [11]. The evaluation of optical properties of the various facetted epilayers is very important in developing an integration technique for electronic and photonic devices on a single substrate. Although a variety of measurements have been employed to determine the electronic states and optical properties, it was difficult to investigate the optical characteristics of the various facetted micro-structures on a single substrate. In this paper, we have reported the optical properties of the micro-facetted InGaAs 281 Mat. Res. Soc. Symp. Proc. Vol. 452 01997 Materials Research Society
QWLs and QWRs grown on V-grooved substrates using magnetophotoluminescence (MPL). Due to the dependence of the quantum confinement states on the magnitude of applied magnetic field, we simply estimate the optical proper
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