Optical and structural behaviour of Mn implanted sapphire

Sapphire single crystals were implanted at room temperature with 180 keV manganese ions to fluences up to 1.8 × 10¹⁷ cm⁻². The samples were annealed at 1000 °C in oxidizing or reducing atmosphere. Surface damage was observed after implantation of low fluences, the amorphous phase being observed after implantation of 5 × 10¹⁶ cm⁻², as seen by Rutherford backscattering spectroscopy under channelling conditions. Thermal treatments in air annealed most of the implantation related defects and promoted the redistribution of the manganese ions, in a mixed oxide phase. X-ray diffraction studies revealed the presence of MnAl₂O₄. On the contrary, similar heat treatments in vacuum led to enhanced out diffusion of Mn while the matrix remained highly damaged. The analysis of laser induced luminescence performed after implantation showed the presence of an intense red emission.     

Proton beam induced luminescence of silicon dioxide implanted with silicon

Light emission from a silicon dioxide layer enriched with silicon has been studied. Samples used had structures made on thermally oxidized silicon substrate wafers. Excess silicon atoms were introduced into a 250-nm-thick silicon dioxide layer via implantation of 60 keV Si⁺ ions up to a fluence of 2 × 10¹⁷ cm⁻². A 15-nm-thick Au layer was used as a top semitransparent electrode. Continuous blue light emission was observed under DC polarization of the structure at 8-12 MV/cm. The blue light emission from the structures was also observed in an ionoluminescence experiment, in which the light emission was caused by irradiation with a H₂⁺ ion beam of energy between 22 and 100 keV. In the case of H₂⁺, on entering the material the ions dissociated into two protons, each carrying on average half of the incident ion energy. The spectra of the emitted light and the dependence of ionoluminescence on proton energy were analyzed and the results were correlated with the concentration profile of implanted silicon atoms.     

Visible light emission from silicon dioxide with implanted excess silicon

Light emission from silicon dioxide doped with excess silicon by silicon ion implantation was investigated. Photoluminescence of silicon dioxide after silicon ion implantation and subsequent annealing at temperatures exceeding 1000 °C was observed. Excitation with monochromatic light with wavelength ranging from λ = 488 nm to λ = 266 nm leads to wide wavelength band emission ranging from about 650 nm up to about 850 nm with a maximum located at about 750 nm. This red/infrared photoemission is attributed to silicon nanocrystals created in silicon dioxide matrix. However, the same material used in electroluminescent experiments emitted blue and green light as well. In this paper the results of photo- and ionoluminescence experiments will be presented. The interest of the paper is focused on the problem of identification of different regions in the structure responsible for light emission of different wavelengths.     

Defects in carbon and oxygen implanted p-type silicon

Both oxygen and carbon ion implantation are frequently used to form either insulating buried SiO₂ or SiC layer for various purposes. This creates a renewal of the interest in defects produced during such implantation processes. In the present paper we report on deep level transient spectroscopy studies of defect states occurring in boron-doped p-type silicon after high dose C⁺ and CO⁺ ion implantation and subsequent thermal annealing. It is shown that the predominant defect created during the implantation is in both cases related to silicon selfinterstitial clusters, which upon annealing at higher temperatures evolve to extended structural defects.     

Soft X-ray spectroscopy of oxide-embedded and functionalized silicon nanocrystals

An X-ray absorption spectroscopic investigation into the electronic and optical properties of silicon nanocrystals (Si-NCs) derived from the thermal processing of hydrogen silsesquioxane (HSQ) is presented. Hydrofluoric (HF) acid etching and subsequent photochemical hydrosilylation with styrene liberates the as-synthesized oxide-embedded Si-NCs from their matrix and renders them solution dispersible through the formation of surface Si–C bonds. The impact of this process on the photoluminescence behavior exhibited by these materials has been studied through near edge X-ray absorption fine structure (NEXAFS) and X-ray excited optical luminescence (XEOL) spectroscopies.     

Surface bioactivity of plasma implanted silicon and amorphous carbon

Plasma immersion ion implantation and deposition (PⅢ&D) has been shown to be an effective technique to enhance the surface bioactivity of materials. In this paper, recent progress made in our laboratory on plasma surface modification single-crystal silicon and amorphous carbon is reviewed. Silicon is the most important material in the integrated circuit industry but its surface biocompatibility has not been investigated in details. We have recently performed hydrogen PⅢ into silicon and observed the biomimetic growth of apatite on its surface in simulated body fluid. Diamond-like carbon (DLC) is widely used in the industry due to its excellent mechanical properties and chemical inertness. The use of this material in biomedical engineering has also attracted much attention. It has been observed in our laboratory that doping DLC with nitrogen by means of PⅢ can improve the surface blood compatibility. The properties as well as in vitro biological test results will be discussed in this article.     

Surface bioactivity of plasma implanted silicon and amorphous carbon

1 Introduction tors.[10,11] In addition, it has been shown that the criti- cal concentration of ionic products dissolved from the Since the discovery of SiO2-based bioglass in bioactive glass composed of soluble silicon and cal-1969,[1] possible applications of silicon-containing cium ions can enhance osteogenesis th…     

Electronic excitations induced modifications of structural and optical properties of ZnO-porous silicon nanocomposites

The influence of swift heavy ion (SHI) irradiation on structural and photoluminescence (PL) properties of ZnO nanocrystallites deposited into porous silicon (PS) templates by the sol-gel process was studied. The ZnO/PS nanocomposites were irradiated using 120 MeV Au ions at different fluences varying from 1 × 10¹² to 1 × 10¹³ ions/cm². The intensity of the X-ray diffraction peaks is suppressed at the high fluence, without evolution of any new peak. The PL emission from PS around 700 nm is found to decrease with increase in ion fluence, while the PL emission from deep level defects of ZnO nanocrystallites is increased with ion fluence. At the highest fluence, the observation of drastic increase in PL emission due to donor/acceptor defects in the region 400-600 nm and suppressions of XRD peaks could be attributed to the defects induced structural modifications of ZnO nanocrystallites.     

Annealing effects in silicon implanted with helium

Silicon samples were implanted with helium and analyzed by atomic force microscopy (AFM) and Raman spectroscopy before and after annealing in the range of 523-1273 K. After annealing at 523 K, the amorphous area induced by He-ion implantation at room temperature was partially recovered and grain sizes became larger. The surface morphology was analyzed through AFM measurements and it was observed that root mean square of the surface roughness alters upwards and then downwards with annealing temperature.     

Electrical and structural characterization of ion implanted GaN

Ion implantation induced defects and their consequent electrical impact have been investigated. Unintentionally doped n-type gallium nitride was implanted with 100 keV Si⁺ and 300 keV Ar⁺ ions in a fluence range of 10¹⁴–10¹⁵ ions/cm². The samples were characterized with Rutherford backscattering/Channeling method for damage buildup. Time of flight elastic recoil detection analysis was implied on the Si implanted samples to see the ion depth distribution. Ar implanted GaN samples were studied electrically with scanning spreading resistance microscopy. Our results show that an Ar fluence of 5 × 10¹⁴ cm^?2 increases the resistance by five orders of magnitude to a maximum value. For the highest fluence, 6 × 10¹⁵ cm^?2, the resistivity decreases by two orders of magnitude.     

Range profiles of implanted Bi and Au in amorphous silicon

The Rutherford backscattering technique is used to measure the depth profiles for 10 to 390 keV ²⁰⁹Bi and 15 to 390 keV ¹⁹⁷Au implanted in amorphized silicon wafers. The obtained projected ranges and projected range stragglings are compared with previous data and with recent universal range-energy calculations. Whereas good agreement is found between the experimental and theoretical range predictions for Bi, the measurements for Au yield, at low energies, ranges longer than predicted. The discrepancy between measured Au and Bi ranges is ascribed to the Z₁-range oscillation.     

Transverse straggling of MeV oxygen ions implanted in silicon

The ¹⁶O(d, α)¹⁴ N nuclear reaction was used to evaluate the lateral dispersion of oxygen ions implanted in silicon with energy ranging from 0.6 to 2 MeV. The projected range and longitudinal straggling, also measured in this experiment, are in close agreement with computer programs like TRIM or PRAL. However, the lateral spread is significantly lower than predicted, saturating towards 0.3 μm for high energies.     

On the lattice location of implanted impurities in silicon

As implanted ions are brought to rest at relatively low energies, one can anticipate that their lattice sites are predominantly determined by the local chemical bond depending on the band structure of the host crystal and the electronic configuration of the implanted impurities. Consequently, one can expect that for a given pure semiconductor the occupancy of various impurity sites will vary with the valency of the impurity atoms. As an example, impurity sites of several groups of nontransition elements of the Periodic Table implanted in silicon are discussed and compared with recent experimental data. Further, a few simple rules concerning the behaviour of implanted impurities in silicon are formulated giving some insight into the nature of the electronic structure of implanted semiconductors.     

Behaviour of implanted oxygen and nitrogen in halogen lamp annealed silicon

The behaviour of oxygen and nitrogen sequentially implanted into silicon at an energy of 100 and 175 keV with total doses of 5 × 10¹⁶ and 2 × 10¹⁷ cm⁻² is reported. The implantation sequence and energies were varied. In all cases the wafer temperature during implantation was maintained at 300°C. The samples were pulse annealed in using a halogen lamp to achieve temperatures of 1100°C and 1200°C for 2–60 s. The samples were analysed using FTIR, XRD and SIMS. For a total dose of 5 × 10¹⁶ cm⁻² no mutual redistribution of oxygen and nitrogen occurs during annealing. The impurity atoms (O and N) are found to bind to radiation defects. Annealing does not lead to any detectable new phase formation but does cause dissociation of oxygen–vacancy complexes and loss of oxygen from the bulk. For a dose of 2 × 10¹⁷ cm⁻² phase formation occurs during implantation. The mutual redistribution of the impurity atoms during annealing occurs but only if oxygen is implanted deeper than nitrogen. This redistribution is greatest if nitrogen is implanted prior to oxygen.     

Defect characterization in boron implanted silicon after flash annealing

Flash-assisted rapid thermal processing (fRTP) has gained considerable interests for fabrication of ultra-shallow junction in silicon. fRTP can significantly reduce boron diffusion, while attaining boron activation at levels beyond the limits of traditional rapid thermal annealing. The efficiency of fRTP for defect annealing, however, needs to be systematically explored. In this study, a (1 0 0) silicon wafer was implanted with 500 eV boron ions to a fluence of 1 × 10¹⁵ cm⁻². fRTP was performed with peak temperatures ranging from 1100 °C to 1300 °C for approximately one milli-second. High resolution transmission electron microscopy and secondary ion mass spectrometry were performed to characterize as-implanted and annealed samples. The study shows that fRTP at 1250 °C can effectively anneal defects without causing boron tail diffusion.     

Interaction between implanted fluorine atoms and point defects in preamorphized silicon

We have studied, by means of B diffusion analyses, the effect of F on the point defect density in preamorphized Si. Through molecular beam epitaxy (MBE) Si samples containing a special B multi-spike were grown. These samples were amorphized to a depth of 550 nm by implanting Si at liquid nitrogen temperature and then enriched with F at different energies (65–150 keV) and fluences (0.7–5 × 10¹⁴/cm²). After solid phase epitaxy (SPE) of the samples, we induced, by thermal annealing at 850 °C, the emission of Si self-interstitials (Is) from the end-of-range (EOR) defects. We studied the diffusion of the B spikes, demonstrating that F effectively reduces the B diffusion. This reduction is shown to be caused not by a direct B–F chemical interaction, but by a F interaction with point defects. In particular, F is able to reduce the density of Is, which are responsible for the B diffusion. Still, we showed that F does not appreciably influence the Is emission from the EOR defects, but a local interaction occurs between F atoms and Is after the release of these defects from the EOR region. This interaction results in a consistent reduction of B diffusivity in F enriched regions.     

The interdiffusion and solid-state reaction of low-energy copper ions implanted in silicon

At room temperature, single-crystal silicon was implanted with Cu⁺ ions at an energy of 80 keV using two doses of 5 × 10¹⁵ and 1 × 10¹⁷ Cu⁺ cm⁻². The samples were heat treated by conventional thermal annealing at different temperatures: 200 °C, 230 °C, 350 °C, 450 °C and 500 °C. The interdiffusion and solid-state reactions between the as-implanted samples and the as-annealed samples were investigated by means of Rutherford backscattering spectrometry (RBS) and X-ray diffraction (XRD). After annealing at 230 °C, the XRD results of the samples (subject to two different doses) showed formation of Cu₃Si. According to RBS, the interdiffusion between Cu and Si atoms after annealing was very insignificant. The reason may be that the formation of Cu₃Si after annealing at 230 °C suppressed further interdiffusion between Si and Cu atoms.     

Investigations of structural, dielectric and optical properties on silicon ion irradiated glycine monophosphate single crystals

The 50 MeV silicon ion irradiation induced modifications on structural, optical and dielectric properties of solution grown glycine monophosphate (GMP) crystals were studied. The high-resolution X-ray diffraction study shows the unaltered value of integrated intensity on irradiation. The dielectric constant as a function of frequency and temperature was studied. UV-visible studies reveal the decrease in bandgap values on irradiation and presence of F-centers. The fluorescence spectrum shows the existence of some energy levels, which remains unaffected after irradiation. The scanning electron micrographs reveal the defects formed on irradiation.     

Growth and structural properties of silicon on Ag films prepared by 40.68 MHz very-high-frequency magnetron sputtering

The growth of silicon on Ag films via 40.68 MHz very-high-frequency (VHF) magnetron sputtering was investigated.The energy distribution and flux density of the ions on the substrate were also measured.The results showed that 40.68 MHz magnetron sputtering can produce ions with higher energy and lower flux density.The impact of these ions onto the grown surface promotes the growth of silicon,which is related to the crystalline nature and rnicrostructure of the underlayer of the Ag films,and there is large particle growth of silicon on Ag films with a preferred orientation of (111),and two-dimensional growth of silicon on Ag films with a better face-centered cubic structure.