Onset of GaSb/GaAs quantum dot formation

Abstract

We present cross-sectional scanning tunneling microscopy results on GaSb nanostructures in GaAs, analyzing their shape, size and chemical composition. By comparing different quantum wells and quantum dot layers, grown both by metalorganic chemical vapor deposition and by molecular beam epitaxy, the onset of quantum dot evolution is studied. Quantum dots are found already after a deposition of 1 monolayer GaSb. Intermixing of the deposited GaSb with GaAs due to anion exchange as well as different effects of Sb segregation during overgrowth are demonstrated.

Probability currents as principal characteristics in the statistical mechanics of non-equilibrium steady states

“…It behoves us to ask whether such fields might be meaningful, and if their properties can be exploited. Pursuing this parallel with electrodynamics far into the future, we may seek an underlying gauge theory [41] and see if it might provide a unified description of all time-dependent phenomena in statistical mechanics.…”

Confined States of Individual Type-II GaSb/GaAs Quantum Rings Studied by Cross-Sectional Scanning Tunneling Spectroscopy

“…Recently, we showed the first atomically resolved structural results on GaSb/GaAs QDs obtained using cross-sectional scanning tunneling microscopy (XSTM) and could unravel the onset of QD formation . For metal−organic chemical vapor deposition (MOCVD), the transition from a 2D quantum well over very small islands to small and compact but optically active QDs was observed. , By using molecular beam epitaxy (MBE), more GaSb material could be accumulated during growth, although this was accompanied by strong group-V exchange effects at the growth surface and significant antimony segregation. , Furthermore, capped GaSb/GaAs QDs grown by MBE under various growth conditions were found to exhibit a ring shape …”

GaSb quantum dot morphology for different growth temperatures and the dissolution effect of the GaAs capping layer

“…Although the issue of capping and its influence on the QDs' properties has been studied extensively, this has been largely restricted to the InAs/GaAs system [18][19][20]. There are only a few papers on the growth of GaSb QDs [14][15][16][17][21][22][23][24][25]32], and the specific issue of capping has not been addressed, even though effects may be more pronounced than in InAs/GaAs. Indeed, our data show that Sb-As exchange during capping is prevalent, and that it leads to dissolution of the dots unless a low capping temperature is used.…”