Optical spectroscopy of self-assembled InP quantum dots grown on GaP using Gas-source molecular beam epitaxy

摘要

This paper describes the growth of and optical emission from InP quantum dots (QD's) grown on (100) GaP using gas-source molecular beam epitaxy. Under the proper growth conditions, the 7.7% lattice mismatch between the strained InP and the GaP buffer drives self-organized island formation through the Stranski-Krastanov mechanism after a critical deposition of InP of approximately 1.8 monolayers (ML's) is exceeded. The photoluminescence (PL) emission from structures with sub-critical InP coverage and, therefore no QD's, consists of two closely spaced, intense, and relatively narrow PL lines in the range of 2.15-2.30 eV. The PL from structures containing InP QD's includes an additional strong emission peak at about 2.0 eV (λ≈620 nm) attributed to radiative recombination of heavy-holes and electrons in the quantum dots. Time-resolved measurements indicate characteristic decay times of several nanoseconds. We believe this is the first report of strong emission from self-organized quantum dots prepared in the GaP system.