Optical and microstructural properties of self-assembled InAs quantum structures in silicon

Abstract

Abstract:The InAs quantum structures were formed in silicon by sequential ion implantation and subsequent thermal annealing. Two kinds of crystalline InAs nanostructures were successfully synthesized: nanodots (NDs) and nanopyramids (NPs). The peaks at 215 and 235 cm −1 , corresponding to the transverse optical (TO) and longitudinal optical (LO) InAs single-phonon modes, respectively, are clearly visible in the Raman spectra. Moreover, the PL band at around 1.3 µm, due to light emission from InAs NDs with an average diameter 7 ± 2 nm, was observed. The InAs NPs were found only in samples annealed for 20 ms at temperatures ranging from 1000 up to 1200°C. The crystallinity and pyramidal shape of InAs quantum structures were confirmed by HRTEM and XRD techniques. The average size of the NPs is 50 nm base and 50 nm height, and they are oriented parallel to the Si (001) planes. The lattice parameter of the NPs increases from 6.051 to 6.055 Å with the annealing temperature increasing from 1100 to 1200°C, due to lattice relaxation. Energy dispersive spectroscopy (EDS) shows almost stoichiometric composition of the InAs NPs. PACS

Ion beam synthesis of embedded III‐As nanocrystals in silicon substrate

“…Therefore, we decided to use RTA to form III-As NCs in Si. As already observed by Prucnal et al [15,16], it is emphasized that the depth profile of arsenic in the (As/In) as-implanted sample is much broader than that predicted from the SRIM simulations due to their diffusion during the In implantation process. The microstructural properties of the GaAs (Fig.…”

“…The As + ions are always implanted first because such a sequence of implantation is expected to result in the formation of smaller NCs with a more uniform size distribution [14]. The nominal dose of As + is fixed to 6x10 16 at.cm -2 for all the samples, with an equal total dose of the column III elements: either only Ga or In for the binary NCs or (Ga + In) for the ternary alloys. In the latter case, Ga is implanted before In.…”

“…Although several compositions were investigated, we focus here only on the results corresponding to the 1 to 1 Ga:In ratio, i.e. to an as-implanted dose of 3x10 16 cm -2 for both Ga and In. After the implantation, the samples are annealed by RTA for 1 min in Ar ambient to promote the growth of the NCs.…”

III–V nanocrystal formation in ion-implanted Ge and Si via liquid phase epitaxy during short-time flash lamp annealing

“…In comparison with Ge, a high number of end-of-range dislocation loops can be seen in cross-sectional TEM images (see Ref. [17]). In addition, nanotwins are observed in the recrystallized Si host.…”

“…The substitution of a conventional furnace or rapid thermal annealing by flash lamp annealing (FLA) obtained better control over size and quality of III-V nanocrystals (NCs) [17]. Further development of this technique yielded a variety of III-V compounds in different material systems ranging from bulk Si [18] over Si thin films [19] to Si-based insulators [20].…”