Uniform and efficient GaAs/AlGaAs quantum dots

Abstract

Uniform arrays of approximately 57 nm diam free-standing quantum dots have been produced from GaAs/AlGaAs single quantum well material by electron-beam lithography and low damage electron cyclotron resonance plasma etching. Low-temperature (5 K) photoluminescence and photoluminescence excitation spectroscopy were used to characterize the material before and after processing into quantum dots. Clear free-exciton features of linewidth comparable to that obtained from the unprocessed material have been observed in the excitation spectra of the quantum dots. As expected for this size of dot, no significant shift in the wavelength of the luminescence was observed, however, there is an apparent enhancement of the external luminescence efficiency when the geometric fill factor is taken into account. The results also show that luminescence efficiency measurements seeking to identify and elucidate intrinsic 0D effects (i.e., those due to quantum confinement in the active region) should be performed with photoexcitation directly into the active region energy states.

Polymer Masks on Semiconductors: A Novel Way to Nanostructures

“…An alternative approach is the use of lithography methods. Recent advantages in electron-, ion-beam and scanning-probe-lithography techniques have pushed the minimum feature size of microfabricated structures down below the 100 nm scale [3]. However, these serial "point by point" techniques are timeconsuming and therefore expensive and tedious.…”

“…Recent advantages in electron-, ion-beam and scanning-probe-lithography techniques have pushed the minimum feature size of microfabricated structures down below the 100 nm scale [3]. However, these serial "point by point" techniques are timeconsuming and therefore expensive and tedious.We report here the use of gold nano-particles prepared and arranged in self-organizing monomicellar diblock copolymer films [4][5][6][7][8] as non-conventional masks in combination with a conventional low-energy reactive ion beam etching (RIBE) process [3]. This technique results in mesoscopic uniform AlGaAs/GaAs and GaAs/InGaAs quantum-…”

Highly-ordered GaAs/AlGaAs quantum-dot arrays on GaAs (001) substrates grown by molecular-beam epitaxy using nanochannel alumina masks

“…Moreover, the SK mode growth is only applicable to highly strained heterostructures, such as InAs/ GaAs, InAs/InP, and Ge/Si, but not to closely lattice-matched heterostructures, such as the technologically important system, GaAs/AlGaAs. Thus fabricating closely lattice-matched heterostructured QD to date has relied on using advanced nanolithography technologies, such as electron beam lithography, [5][6][7] which is a high-cost and low-throughput ͑se-rial writing͒ approach. Recently, photolithography based on interferometry has progressed remarkably and shown to be capable of realizing sub-100-nm resolution; 8 selective molecular-beam epitaxial ͑MBE͒ growth of GaAs and InAs nanodots has been demonstrated on GaAs substrates using SiO 2 masking.…”

Positional control of self-assembled quantum dots by patterning nanoscale SiN islands

“…1,2 Recently, quantum dots have been attracting considerable attention as a possible candidate for use in quantum computation and quantum communication. 2,5,6 Self-assembled quantum dots, which require only crystal-growth techniques for fabrication, are currently one of the best structures for characterizing the physics, demonstrating quantum processes, and application to optical devices. 2,5,6 Self-assembled quantum dots, which require only crystal-growth techniques for fabrication, are currently one of the best structures for characterizing the physics, demonstrating quantum processes, and application to optical devices.…”