Newman, R.C.R.C.NewmanAshwin, M.J.M.J.AshwinFahy, M.R.M.R.FahyHart, L.L.HartHolmes, S.N.S.N.HolmesRoberts, C.C.RobertsZhang, X.X.ZhangWagner, J.J.Wagner2022-03-032022-03-031996https://publica.fraunhofer.de/handle/publica/18858910.1103/PhysRevB.54.8769Low-noise infrared (IR) absorption measurements of localized vibrational modes (LVM's) showed that SiAs acceptors, SiGA-SiAs pairs, and a deep trap Si-X (VGa-SiAs-AsGa), as well as isolated SiGa donors, were present in silicon delta-doping superlattices in (001) GaAs grown under an As flux by molecular-beam epitaxy (MBE) at 400 deg C for areal concentrations (per layer) 0.05 ML<= (Si)A <= 0.5 ML. These observations supersede previous data, and agree with recent Raman-scattering measurements. For [Si]A<=0.5 ML, the LVM's were not detected by either technique, but Raman measurements revealed a broad line that has been attributed to small two-dimensional Si clusters. For [Si]A <= 0.5 ML, electrical conductivity was lost. These observations led to a reappraisal of simulations of high-resolution x-ray 002 and 004 diffraction profiles. IR and Raman measurements for delta-doping superlattices that all have [Si]A <= 0.01 ML (per layer) showed only the SiGa LVM as the interlayer spacing was red uced to 5 ML when the volume carrier concentration n approached about 2 x 10(exp 19) cm(exp -3). For interlayer spacings of 2 and 1 ML, compensating complexes SiAs, SiGa-SiAs, and Si-X were present, and n tended to zero. Compensating complexes were also present in homogeneously doped MBE GaAs grown at 350 deg C, but n remained at a value of 2 x 10(exp 19) cm(exp -3) as [Si] was increased to 1.3 x 10(exp 20) cm(exp -3). N never exceeded 2 x 10(exp 19) cm(exp -3) in any sample. The formation of VGa, AsGa, etc. is attributed to diffusion jumps of Si atoms originally located on Ga lattice sites. The formation of the "Si-like" structure in delta layers must result from the aggregation of such displaced atoms. We speculate that these processes are facilitated by the initial displacements of SiGa donors to DX locations.enGaAsRöntgendiffraktometrieSi delta-dopingSi-Deltadotierungx-ray diffraction621667530journal article