Self-Assembly of GaAs Quantum Wires Grown on (311)A Substrates by Droplet Epitaxy

We report the formation of GaAs quantum wires (QWRs) on (311)A substrates by droplet epitaxy. High-density quantum dots coalesce to form wires oriented along the $[\bar{2}33]$ direction as a result of atom diffusion triggered by thermal annealing. Luminescence from the QWRs is significantly polarize...

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Published inApplied physics express Vol. 4; no. 5; pp. 055501 - 055501-3
Main Authors Jo, Masafumi, Keizer, Joris. G, Mano, Takaaki, Koenraad, Paul M, Sakoda, Kazuaki
Format Journal Article
LanguageEnglish
Published The Japan Society of Applied Physics 01.05.2011
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Summary:We report the formation of GaAs quantum wires (QWRs) on (311)A substrates by droplet epitaxy. High-density quantum dots coalesce to form wires oriented along the $[\bar{2}33]$ direction as a result of atom diffusion triggered by thermal annealing. Luminescence from the QWRs is significantly polarized parallel to the wire direction, which would result in higher gain in lasers that use cleaved $(01\bar{1})$ surfaces as Fabry--Pérot mirrors. Lasing is obtained for a GaAs/AlGaAs QWR laser diode with fivefold-stacked QWR layers under pulsed operation at a low temperature.
Bibliography:(a)--(c) $400\times 400$-nm AFM images of GaAs QDs annealed at different temperatures: (a) 450, (b) 500, and (c) 550 °C. The height contrast is 3 nm. (d) A cross-sectional profile of the AFM image in (c), taken along the $[01\bar{1}]$ direction. (e) Fourier transform of the profile in (e) using a cutoff length of 100 nm. The spatial period of 27 nm is close to the average wire width of 25 nm observed in (d). (f) $43\times 190$-nm topographic XSTM image of a QWR formed at 550 °C annealing. The image was taken at $V = -2.6$ V and $I = 40$ pA. The bright (dark) region corresponds to GaAs (AlGaAs). The bright spot near the center stems from an adsorbate to the surface. (g) $19\times 20$-nm closeup of the QWR. Polarization-resolved PL spectra of GaAs QWRs at 6 K. The inset shows a $500\times 500$-nm bird's-eye view of GaAs QWRs. $L$--$I$ characteristics of the GaAs/AlGaAs QWR laser diode under pulsed operation (0.01% duty cycle, pulse width of 1 μs) at 77 K. The inset shows the EL spectra below and above the threshold current density of 8.9 kA cm -2 .
ISSN:1882-0778
1882-0786
DOI:10.1143/APEX.4.055501