Structure and Optical Properties of Si/InAs/Si Layers Grown by MBE on Si Substrate at Different Temperatures
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Institute of Microstructure Physics, 06120 Halle/Saale, zakharov(&mpi-halle.de, GERMANY; "**TechnicalUniversity of Berlin, Berlin, GERMANY ***A.F.Ioffe Phisico-Technical Institute RAS, St.Petersburg, RUSSIA
Weinberg
2,
ABSTRACT Epitaxial Si/InAs/Si heterostructure grown on (001) Si substrate by molecular beam epitaxy (MBE) and annealed at 800'C, and 880'C were investigated by High Resolution Transmission Electron Microscopy (HRTEM). Extensive interdiffusion at 800°C leads to the formation of an InAs solid solution as well as InAs-enriched regions with extensions of -6nm, which exhibit two kinds of ordering. The ordering of InAs molecules occurred, respectively, in 1 10} planes inclined and parallel to the [001] growth direction. It is attributed to the energy gain from the reduced number of mixed Si-As and Si-In bonds. The sample grown at 800'C shows photoluminescence in the 1.3.tm region, which is tentatively attributed to the recombination of excitons localised in the ordered regions. INTRODUCTION The potential benefit from combining the advantageous optical properties and flexibility of Ill-V semiconductors with silicon technology widely used in microelectronics has attracted great interest for decades. Up to now, researchers have focussed on the growth of continuos layers of III-V materials on silicon [1]. The large misfit Ebetween Si and, e.g., InAs (F=10.6%) renders the growth of electronic or optical quality material practically unresolvable problem. More recently, the possibility to exploit the formation of narrow-gap I1l-V islands on Si substrates has been pointed out [2]. Indeed, such small InAs islands on Si(100) surface have been observed by scanning tunnelling microscopy [3] and high-resolution transmission electron microscopy (HRTEM) [4]. HRTEM investigations of capped InAs/Si structures [5,6] revealed a high density of coherent InAs clusters with typical dimensions in the 3nm region at the InAs/Si interface for optimised growth conditions. Such samples exhibit a broad photoluminescence (PL) peak in the 1.3 p.m region at 10 K [3]. Detailed optical investigations of this PL line indicated a k-indirect type II transition [7], which has been tentatively attributed to excitons localised in the small coherent InAs clusters [7]. The extreme small size (0
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