Formation of self-assembling CdSe quantum dots on ZnSe by molecular beam epitaxy

Abstract

We report the formation of self-assembling CdSe quantum dots during molecular beam epitaxial growth on ZnSe and ZnMnSe. Atomic force microscopy measurements on specimens with uncapped dots show relatively narrow dot size distributions, with typical dot diameters of 40±5 nm, and with a diameter-to-height ratio consistently very close to 4:1. Uncapped CdSe dots are unstable with time: their density was observed to drop by an order of magnitude in 10 days, with clear evidence of ripening observed for some dots. Photoluminescence from capped dots indicates exciton localization much stronger than in ZnCdSe/ZnSe quantum wells, due to the additional lateral confinement.

Resonant spectroscopy of II-VI self-assembled quantum dots: Excited states and exciton–longitudinal optical phonon coupling

“…A 50 nm thick ZnSe (ZnTe) capping layer covered the dot layer. Further details of the sample growth and their optical characterization can be found elsewhere [16,17]. It is important to note that the sample set chosen enables us to study QDs with considerably different lateral sizes.…”

Self-ordered CdSe quantum dots in ZnSe and (Zn, Mn)Se Matrices Assessed by transmission electron microscopy and photoluminescence spectroscopy

“…(Zn,Mn)Se rather than pure ZnSe matrices have been found to be beneficial for the growth of the QDs 12,13 , leading to dilute magnetic semiconductors 14 whose luminescence properties can be controlled by a magnetic field. Recently, fractional monolayers (ML) of BeSe have been used to induce the growth of 3D CdSe islands/QDs at a thickness region of the WL that usually leads only to the formation of a 2D quantum well 15 .…”

Exciton dephasing and biexciton binding in CdSe/ZnSe islands

“…[1][2][3] The optical properties of such islands have been mainly studied by incoherent methods. [4][5][6][7] Driven by the search for blue-green-emitting semiconductor materials, the fabrication [8][9][10][11][12][13] and optical characterization [14][15][16][17][18] of self-assembled II-VI islands have recently been the subject of intensive research. Only little is known about the coherent properties of these structures, giving information about exciton scattering and biexciton formation.…”