AVS 50th International Symposium
    Semiconductors Friday Sessions
       Session SC+NS-FrM

Paper SC+NS-FrM4
Tuning of the Electronic Properties of Self-assembled InAs/InP(001) Quantum Dots by Rapid Thermal Annealing and Low-energy Ion Implantation

Friday, November 7, 2003, 9:20 am, Room 321/322

Session: Low Dimensional Structures and Amorphous Silicon
Presenter: C. Dion, École Polytechnique de Montréal, Canada
Authors: C. Dion, École Polytechnique de Montréal, Canada
C. Nì Allen, National Research Council, Canada
S. Raymond, National Research Council, Canada
P.J. Poole, National Research Council, Canada
F. Schiettekatte, Université de Montréal, Canada
R.A. Masut, École Polytechnique de Montréal, Canada
P. Desjardins, École Polytechnique de Montréal, Canada
Correspondent: Click to Email
We have investigated the effect of post-growth rapid thermal annealing on the low temperature photoluminescence (PL) spectra of self-assembled InAs/InP(001) quantum dots (QD) grown by chemical beam epitaxy (CBE) and metal-organic vapor phase epitaxy (MOVPE). Annealing temperatures T@sub a@ and times t@sub a@ ranged from 650 to 800 °C and 30 to 210 s, respectively. As-grown samples are characterized by a broad emission peak centered near 800-900 meV arising from the e1-hh1 transition of an ensemble of QDs and a narrow peak near 1100 meV from radiative recombination in the wetting layer. Detailed analysis of the QD PL emission reveals that it is composed of up to 9 peaks corresponding to families of dots emitting at different energies. A blueshift of the QD transitions, resulting from intermixing, is observed upon annealing. It increases with T@sub a@ and t@sub a@; blueshifts of up to 90-100 meV are obtained for annealing time of 210s at 800 °C. While the PL emission energies of the various QD families shift at different rates upon annealing, their width remains constant. This behavior is consistent with inhomogeneous broadening dominated by monolayer height fluctuations in InAs/InP(001) dots. In order to obtain larger blueshifts, we studied the effect of introducing point defects into thick InP cap layers, either by growing InP at low temperature or by implanting P at energies sufficiently low to insure that the InAs QDs are not damaged. Such point defects, located far from the QDs, dramatically increase diffusion rates; shifts of up to 250 meV have been obtained following annealing at 765 °C for 90 s.