Silicon Nanostructures in Si-Based Light-Emithing Devices (original) (raw)
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Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1991
A detailed study of near-gap photoluminescence (PL) from strained Si 1 xGe" alloy layers (x = 0.01-0.05) and SilSi o. 95 Ge O. 05 muIti-quantum~wells (MQWs) has failed to show either freeor dopant-bound excitons in as-molecular-beam-epitaxy-prepared epitaxial layers. Lowtemperature PL was, however, successfully induced in these same heterostructures by the selective introduction of relatively shallow radiation-damage bound-exciton centers, I, and G (137 and 186 meV deep, respectively). The II center, in particular, produced broadened spectra which are shown clearly to emanate from the epitaxial layers, with separate and distinguishable components originating from both the Si and the Si 1 xGe x (x = 0.01-0.05) layers. This is among the first such reports of luminescence verifiably originating from within a Sil8i 1 _ x Ge" multiple heterostructure. Importantly, we find that this defect-induced PL is not significantly diminished (or even significantly influenced) by the addition of multiple heterointerfaces, thus leading to the conclusion that heterointerface quality may be good. This indicates that these heterointerfaces are not the source of the competing nonradiative recombination which likely prevents the observation of near-gap PL, which is instead possibly due to bulk defects.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1997
Low temperature (2 K) photoluminescence (PL) properties of epitaxial Si i _,Ge, and Si, _,l_yGexCy layers on Si (x = 0.13 and y = 0.014 at peak concentration) formed by ion beam synthesis (IBS) have been investigated. Samples were prepared by a high-dose Ge with/without C ion implantation (12) at room temperature and by subsequent three different crystallization techniques: (i) furnace annealing (FA) process up to 84O"C, (ii) ion beam-induced epitaxial crystallization (IBIEC) process with 400 keV Ge or Ar ions at 300-350°C. and IBIEC process followed by FA process up to 640°C (IBIEC + FA). Although FA-grown Si,_,_,Ge,C, samples showed G-line (C,-Sii -C, complex) emission at 0.969 eV, IBIEC-grown samples presented a sharp I 1 non-phonon emission at 1 .O 193 eV. This indicates that C atoms agglomeration is dominant for FA-grown samples, while a creation of trigonal tetravacancy cluster is dominant for IBIEC-grown samples. On the other hand, (IBIEC with Ge ions + FA)-grown Si, _,_,,GerC y samples showed neither G-line nor I,-related emissions,
Si-Based Photonic Devices by MBE
MRS Proceedings, 1991
ABSTRACTThe prospect of efficient electroluminescence and photodetection in Si-based heterostructures has stimulated considerable interest in recent years. Si-based optoelectronic devices would allow monolithic integration of mature Si technology with optical signal processing. However, Si and epitaxial Si1−xGex/Si (100) alloys are indirect semiconductors and band structure perturbations are necessary to enhance luminescence efficiencies to practical levels. In this review we consider the relative success of the various approaches used to obtain efficient luminescence from Si based heterostructures after first considering the optical properties of Si grown by MBE and doped by several techniques. Exciton binding centers such as isoelectronic defect complexes, zone folding in atomic layer superlattices, e.g. SimGen, and rare earth doping, e.g. Er in Si and Si1−xGex alloys are discussed. The internal quantum efficiencies for the above processes will be compared in both electroluminesce...
Photoluminescence from Coherently Strained Si1−xGex Alloys
MRS Proceedings, 1990
ABSTRACTAn intense, broad photoluminescence PL peak, with an internal quantum efficiency as high as 31%, has been observed from a variety of structures containing Si1−xGex strained layers on Si(100) substrates; i.e. Si1−xGex thick random alloy layers, single quantum wells (SQW) and multiple quantum wells (MQW) with layers thick enough so that zone folding effects were not relevant. This peak, which shifted consistently and predictably with Ge concentration( 0.06 < × < 0.53), had its high energy edge near the established band gap for strained SiGe. PL excitation spectroscopy indicated that no phonons were involved in the process causing the SiGe PL peak. Samples deposited at ~ 400 °C exhibited low PL intensity, whereas annealing at ~ 600 °C enhanced the intensity by as much as two orders of magnitude. This anneal treatment was found to remove grown-in defect complexes without creating a significant density of misfit dislocations. The PL peak energy at 4.2 K varied from 620 to 9...
Effect of rapid thermal annealing on the photoluminescence properties of SiGe/Si heterostructures
Journal of Applied Physics, 1995
The effect of growth temperature and thermal treatments on the luminescence properties of SiGe/Si heterostructures grown by'rapid thermal chemical-vapor deposition is reported. While the excitonic luminescence of the strained Sit-,Ge, layer is observed in the samples grown above 700 "C, the signal completely disappears for deposition temperatures lower than 650 "C. After rapid thermal annealing, we show that a drastic improvement of the luminescence efficiency of the layers deposited at low temperatures is obtained. A spectral blue shift of the excitonic luminescence can also be observed and is interpreted in terms of interdiffusion of Si and Ge atoms during the heating process. The photoluminescence spectra after a rapid thermal annealing at 1050 "C have been used for the first time to perform an accurate study of the thermal stability of strained Si0s5Ge0.15 alloys. It is shown that when the layers are in a metastable state before annealing, the relaxation phenomenon leads to a photoluminescence signal which consists of both band-edge and dislocation-related recombinations. In this case, the strain relaxation is mainly attributed to the formation of misfit dislocations at the SiGe/Si heterointerface. In very thin SiGe layers, only the band-edge luminescence can be observed, but it is shifted to the high-energy side as expected by the interdiffusion model. Using a simple theoretical approach, this shift can be used to calculate the interdiffusion coefficient in good agreement with the literature data.