There is significant interest in developing microelectronic devices for blue emission, high temperature, high power, high frequency, and radiation hard applications. This interest has generated significant research effort in wide bandgap semiconductor material, in particular S i c and semiconducting diamond. Both of these materials are similar in crystal structure with half of the carbon atoms in the diamond structure replaced by Si to produce Sic. However, the latter material exists in a host of polytypes, the causes of which are not completely understood. The deposition of monocrystalline diamond at or below 1 atm total pressure at T
We report a study of self-assembled quantum dots (QDs) of InSb embedded in a GaSb matrix grown by metalorganic vapor phase deposition. Growth temperatures and deposition times have been optimized for maximal photoluminescence peak intensities. Photoluminescence (PL), magneto-PL, and atomic force microscopy (AFM) have been performed to estimate the size of the QDs. The quantum dots luminesce in the midinfrared at around 0.73 eV. The application of magnetic fields up to 15 T both parallel and perpendicular to the growth direction enhanced the wetting layer and bulk PL intensity and enabled an estimate to be made of the QD height and widths as 2–4 and 20–30 nm, respectively. These sizes were confirmed by AFM.
Atomic scale analysis of Sn quantum dots ͑QDs͒ formed during the molecular beam-epitaxy ͑MBE͒ growth of Sn x Si 1Ϫx (0.05рxр0.1) multilayers in a Si matrix revealed a void-mediated formation mechanism. Voids below the Si surface are induced by the lattice mismatch strain between Sn x Si 1Ϫx layers and Si, taking on their equilibrium tetrakaidecahedron shape. The diffusion of Sn atoms into these voids leads to an initial rapid coarsening of quantum dots during annealing. Since this formation process is not restricted to Sn, a method to grow QDs may be developed by controlling the formation of voids and the diffusion of materials into these voids during MBE growth.
Single and multilayer sheets of self-assembled CdSe (QDs) were grown by means of molecular beam epitaxy in both ZnSe and (Zn 0.9 Mn 0.1 )Se matrices. Both types of structures were assessed by means of transmission electron microscopy in the scanning, high-resolution, and diffraction-contrast modes.Complementary results from wider sample areas were obtained by means of photoluminescence spectroscopy. In one of the samples analyzed, a fractional monolayer of MnSe was deposited immediately before the CdSe deposition. A second structure grown under identical conditions, but without the MnSe fractional monolayer was also analyzed. This comparison provides direct evidence for an enhanced size and shape homogeneity of 3D QDs caused by the presence of a tiny amount of MnSe at the interface. In the multilayer structure, we observed the co-existence of highly strained quasi-2D QDs and CdSe rich aggregates with compositional modulations on certain crystallographic planes in close proximity.
Highly uniform (Cd,Mn,Zn)Se/(Zn,Mn)Se quantum dot array formation by means of thermal treatments Nano-agglomerates of In͑Sb,As͒ in InAs, ͑In,Ga͒Sb in GaSb, and ͑Cd,Zn,Mn͒Se in ͑Zn,Mn͒Se are classified by transmission electron microscopy. In scanning transmission electron microscopy, atomic resolution Z-contrast images reveal different modes of internal compositional modulation on the atomic length scale, resulting for all three material systems in nano-agglomerates of an appropriate size that may constitute a new type of quantum dot. For other nano-agglomerates of In͑Sb,As͒ in InAs and ͑In,Ga͒Sb in GaSb, we observed a second type of nanoscale ordering that results in nano-agglomerates with an internal compositional modulation on a length scale of a few nm. Both types of compositional modulation are discussed as having arisen from a rather long-term structural response to a combination of internal and external strains.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.