Optical spectroscopy of single InAs/InGaAs quantum dots in a quantum well

Abstract

We have grown self-assembled InAs quantum dots embedded in the center of an InGaAs quantum well by molecular-beam epitaxy. Using electron-beam lithography and wet etching techniques, small mesas with only a few quantum dots were fabricated. At room temperature, the quantum dots have an emission wavelength of 1.3 μm. By photoluminescence spectroscopy at low temperatures, we observe the emission lines of excitons and biexcitons in single-dot structures. The assignment of exciton and biexciton recombination is based on the characteristic excitation intensity dependence of these states. A biexciton binding energy of about 3.5 meV is obtained for the present dots.

Growth and characterization of single quantum dots emitting at 1300 nm

“…Progress in this direction has been slow, due to the difficulty of growing sufficiently large and In-rich InAs/ GaAs QDs for emission in the infrared, and because of the lower signal-to-noise performance of detectors in this wavelength range. Clear single QD emission ͑as proved by exciton-biexciton dynamics͒ was only demonstrated up to 1150 nm, 4 while discrete lines with unclear pump power dependence were reported for QDs emitting at 1300 and 1550 nm. 5,6 In this letter, we describe a growth method which provides, at the same time, a low QD density in the 2-3 m −2 range and an emission wavelength of 1300 nm at low temperature ͓i.e., ϳ1400 nm at room temperature ͑RT͔͒.…”

“…The deviation from the ideal linear and quadratic dependencies has been observed before in QDs capped with InGaAs. 4 However the fact that I XX ϰ I X 2 ͑see inset in In͑Ga͒As/ GaAs QDs ͑from negatives values up to about 5 meV͒ 12 as determined by the balance of Coulomb interaction, correlation, and exchange. Other sharp lines appear at higher excitation power.…”

Charged exciton emission at 1.3μm from single InAs quantum dots grown by metalorganic chemical vapor deposition

“…Efficient single-photon emission has recently been demonstrated at visible wavelengths using semiconductor QD structures, 1,2,3 and there have been many detailed investigations into the low-temperature optical characteristics of QDs emitting at 1150 nm or less. 4,5,6 However, to date there have been only a small number of spectroscopic experiments on single QDs emitting in the important telecommunications window around 1300 nm: 7 biexcitonic features have been identified in low-temperature photoluminescence (PL) from QDs grown by molecular beam epitaxy (MBE), 8 whereas similar investigations for QDs fabricated by metalorganic chemical vapor deposition (MOCVD) show an unclear power dependence in the emission. 9 Quantum dot structures grown by MOCVD have potentially a large commercial value due to the high growth rates achievable; however, for applications at telecommunication wavelengths the growth is complicated by large strain effects and complex surface dynamics within the dot layers.…”

Optical probe of InAs/GaAs self-assembled quantum dots grown using low growth rate and growth interruptions

“…It is ascribed to the decay of biexcitons, XX, because the integrated PL intensity exhibits a superlinear behavior with respect to P D , and a slope equal to 1.65. The deviation from the ideal quadratic dependence has already been observed for several quantum dots structures [16,22,27,28]. Additionally, since the biexcitons binding energy values have been reported to fall within the range of 1-4 meV for InGaAs/ GaAs QDs [16,25,27], the biexcitons luminescence could be paired either with P1 or P2.…”