Density dependent composition of InAs quantum dots extracted from grazing incidence x-ray diffraction measurements.
Epitaxial InAs quantum dots grown on GaAs substrate are being used in several applications ranging from quantum communications to solar cells. The growth mechanism of these dots also helps us to explore fundamental aspects of self-organized processes. Here we show that composition and strain profile of the quantum dots can be tuned by controlling in-plane density of the dots over the substrate with the help of substrate-temperature profile. The compositional profile extracted from grazing incidence x-ray measurements show substantial amount of inter-diffusion of Ga and In within the QD as a function of height in the low-density region giving rise to higher variation of lattice parameters. The QDs grown with high in-plane density show much less spread in lattice parameter giving almost flat density of In over the entire height of an average QD and much narrower photoluminescence (PL) line. The results have been verified with three different amounts of In deposition giving systematic variation of the In composition as a function of average quantum dot height and average energy of PL emission.
Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, 700064, Kolkata, India.
Manjula
M
Sharma
Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, 700064, Kolkata, India.
Milan K
MK
Sanyal
Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge, CB3 0HE, United Kingdom.
Ian
I
Farrer
Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge, CB3 0HE, United Kingdom.
David A
DA
Ritchie
Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, 700064, Kolkata, India.
Arka B
AB
Dey
Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, 700064, Kolkata, India.
Arpan
A
Bhattacharyya
Deutsches Elektronen-Synchrotron, DESY, Notkestrasse 85, 22607, Hamburg, Germany.
Oliver H
OH
Seeck
Toshiba Research Europe Limited, Cambridge Research Laboratory, 208 Science Park, Milton Road, Cambridge, CB4 0GZ, United Kingdom.
Joanna
J
Skiba-Szymanska
Toshiba Research Europe Limited, Cambridge Research Laboratory, 208 Science Park, Milton Road, Cambridge, CB4 0GZ, United Kingdom.
Martin
M
Felle
Toshiba Research Europe Limited, Cambridge Research Laboratory, 208 Science Park, Milton Road, Cambridge, CB4 0GZ, United Kingdom.
Anthony J
AJ
Bennett
Toshiba Research Europe Limited, Cambridge Research Laboratory, 208 Science Park, Milton Road, Cambridge, CB4 0GZ, United Kingdom.
Andrew J
AJ
Shields