InAs/GaAs Quantum Dots Grown by Metalorganic Chemical Vapor Deposition

Abstract

InAs quantum dots (QDs) have been grown by metalorganic chemical vapor deposition on exactly (001) oriented GaAs using the Stranski-Krastanow growth mode. The samples exhibit a high average dot density of 4 ×1010 cm-2 with no defects over macroscopic areas. The QDs show bright room temperature luminescence at around 1.1 eV. Vertical dot stacks consisting of up to 5 QD sheets with various GaAs separation layer thicknesses have been produced. Transmission eletron microscope images show pronounced QD ordering in the growth direction. For thin separation layers the dot luminescence is red shifted by ∼ 70 meV for the stacked dots as compared to single dot sheets. A low threshold (100 A/cm2 at 77 K) separate confinement heterojunction laser with a five-fold dot stack as an active medium operating at up to room temperature is demonstrated.

Role of elastic anisotropy in the vertical alignment of In(Ga)As quantum dot superlattices

“…4,[6][7][8][9][10][11] It has often been proposed that this vertical elastic interaction can lead to lateral ordering and size homogenization of the islands. 1,2,4,10 However, under close examination quite the opposite is observed, i.e., in vertically correlated In͑Ga͒As stacks subsequent QDs grow larger and even splitting can occur.…”

Intersubband absorption in p-type Si1−xGex quantum dots on pre-patterned Si substrates made by a diblock copolymer process

“…Such SAQDs have poor lateral confinement, causing them to have non-ideal normal-incidence absorption characteristics, similar to quantum wells. In this article, we report the observation of the intersubband absorption in valence bands of Si 1Àx Ge x quantum dots with base dimensions of about 15 nm, heights of 5-7 nm, and an aerial dot density of approximately 10 11 …”

“…Such quantum dots can be realized using self-assembly in the StranskiKrastanov growth mode. Self-assembled quantum dots (SAQDs) based on the Stranski-Krastanov growth mode have been intensely studied [10][11][12]. However, SAQDs are pancake-like dots with large base dimensions of 50-100 nm, heights of 7-10 nm, and low aerial dot density of 10 9 -10 10 cm À2 .…”

The role of arsine in the self-assembled growth of InAs∕GaAs quantum dots by metal organic chemical vapor deposition

“…It is generally accepted in epitaxial growth of lattice matched systems that a lower AsH 3 flow increases the adatom mobility. 3 However, for MOCVD growth of InAs/ GaAs quantum dots, a higher AsH 3 flow typically results in island ripening and increased island size, suggesting a higher adatom mobility [4][5][6] This effect has been attributed to several factors. The works by Heinrichsdorff et al 5 and Steimetz et al 7 suggest that the presence of atomic hydrogen leads to increased clustering and QD ripening, possibly through a destablization effect of the wetting layer.…”

“…3 However, for MOCVD growth of InAs/ GaAs quantum dots, a higher AsH 3 flow typically results in island ripening and increased island size, suggesting a higher adatom mobility [4][5][6] This effect has been attributed to several factors. The works by Heinrichsdorff et al 5 and Steimetz et al 7 suggest that the presence of atomic hydrogen leads to increased clustering and QD ripening, possibly through a destablization effect of the wetting layer. In MOCVD growth using hydrides as the group V source, an increased V/III ratio is also always associated with an increased concentration of atomic hydrogen which is not present in MBE growth.…”