Impurity-free disordering of InAs∕InP quantum dots

Abstract

Impurity-free disordering ͑IFD͒ of the InAs quantum dots ͑QDs͒ capped with either an InP layer or an InGaAs/ InP bilayer is studied. The samples are coated with a SiO 2 or TiO 2 dielectric layer followed by rapid thermal annealing at 700, 750, 800, and 850°C for 30 s. A large differential energy shift of 157 meV is induced by SiO 2 in the QDs capped with an InGaAs/ InP bilayer. Contrary to the reported results on the suppression of intermixing of GaAs based QDs by TiO 2 , the authors find that intermixing of InAs/ InP QDs is promoted by TiO 2. X-ray photoelectron spectroscopy depth profiles show that both In and P outdiffuse to a TiO 2 layer whereas Ga, In, and P outdiffuse to a SiO 2 layer leading to different degrees of intermixing. The results indicate that a group V interstitial diffusion mechanism might be responsible for IFD of InAs/ InP QDs.

Surface and interface study of SiO2-x coated InP/InGaAs/InGaAsP semiconductor laser microstructures processed in the soft KrF laser irradiation regime

“…The SiO 2-x /InP interface 2 is the surface after interface 1 sputtered for another 60 seconds and the average sputtering speed in InP is estimated to be 0.5 nm/second. In contrast to earlier reported results, 10,19 no In 3d (445 eV, red line) and P 2s (187 eV, green line) are found in the SiO 2-x layer. Furthermore, a weak In 3d (0.35 %) but no P 2s peaks are found at the SiO 2-x /InP interface 1.…”

“…This is in contrast to the impurity free vacancy induced disordering effect observed in InP-based MQW microstructures that were RTA at 800-850°C for 2-3 minutes. 10,9 The related experiments have reported the presence of In and Ga atoms outdiffused to the cap SiO 2 layer at ≥ 0.5 at.%. Thus, the argument was made that the left behind group III vacancies or group V interstitials were responsible for an enhanced intermixing process.…”

“…% while a negligible presence of P atoms has been found in SiO 2 . 10 This results in the excess of P and As interstitials in the QW region and leads to an enhanced intermixing process.…”

InP-based photonic circuits: Comparison of monolithic integration techniques

“…This opens up an interesting route to using this advanced material in photonic integrated circuits [34].…”

Vacancy-mediated intermixing in InAs/InP(001) quantum dots subjected to ion implantation

“…Given that the evolution of the photoluminescence ͑PL͒ characteristics with annealing time and temperature is similar for dielectric capping, GID, and low-energy ion implantation ͑LEII͒, it was assumed by several authors that the dominant defects responsible for intermixing in InGaAs/InP quantum wells ͑QWs͒ were P interstitials. 4,8 In InAs/InP QDs, intermixing using conventional annealing, 9 laser annealing, 10 dielectric capping, [10][11][12] and GID 13 generally resulted in a progressive blueshift of the overall QD emission spectra with no significant peak broadening. In sharp contrast, intermixing stimulated by the creation of defects in the capping layer using ion implantation yielded significant bandwidth broadening of the emission spectra.…”