Doping of diamond by coimplantation of carbon and boron

Type IIa diamond crystals were implanted with boron ions with or without prior carbon ion implantation. The samples were kept at liquid nitrogen temperature during both implantation steps. A strong near-edge optical absorption band appeared after implantation, and partially recovered during annealing at 800 °C. For the highest B implantation fluence, optical absorption peaks at 2800 to 3000 cm-1 were observed that were in the same vicinity as the absorption peaks attributed to substitutional boron atoms in natural p-type diamond. Electrical measurements for three of the samples demonstrated well-defined activation energies that could be associated with hopping conduction and/or activation of B dopant atoms. This work shows that p-type doping in diamond by boron ion implantation is feasible, using a suitable combination of low temperature implantation and subsequent annealing.

Correlation between damage evolution, cluster formation and optical properties of silver implanted lithium niobate

Carbon ions were implanted in a nickel thin film. After subsequent rapid thermal annealing, they segregated on the surface, forming a graphene layer. The dependence of graphene synthesis on process conditions, including the carbon implantation dose, RTA temperature, and time, were investigated. The graphene shows quality comparable to that of the best reported CVD graphene. It was also found that local growth of graphene through local implantation requires stringent control of the process chamber conditions in order to avoid growth of graphene on unimplanted regions.

ABSTRACTIt has been a challenge to inject dopant atoms onto diamond lattice sites by ion implantation, because of the complications of ion damage and defect clustering during annealing. We re-investigated this topic by implanting boron ions into an insulating natural diamond ( type II-A ) which was predamaged by carbon ion implantation. Both of the implantations were performed at liquid nitrogen temperature. The amount of pre-damage was adjusted to produce enough vacancies and interstitials in diamond to promote boron substitutionality during subsequent annealing. Samples were characterized by optical absorption and electrical measurements. It was found that optical absorption of the implanted samples strongly depends on the post implant annealing sequence. The activation energies obtained from electrical measurements match very closely to those due to boron atoms in natural p-type diamonds. Photoconductivity measurements showed that the fraction of remaining electrically active radiation defects in the implanted and annealed samples depends on the relative fluences of boron and carbon.

Influence of impurities on ion beam induced TiSi 2 formation

XTEM characterization of tungsten implanted SiC thin films on silicon for field emission devices

Silicon samples containing a sequence of boron spikes grown by molecular beam epitaxy have been used in this work. Point defects were introduced near the surface by means of room temperature silicon implantation. The ion profile was confined between the surface and the first boron spike. The presence of self-interstitials enhances the boron diffusion in ion-implanted and subsequently annealed samples. Two kinds of thermal annealing were used for this study on implanted samples: a mid-temperature annealing (700°C, 20min) and a rapid thermal annealing (950°C, 20s). The aim of the present study was to investigate if a mid-temperature annealing could significantly reduce boron diffusion during a subsequent rapid thermal annealing. It is shown in this work that the slight reduction in interstitial excess concentration during the mid-temperature annealing is not sufficient to substantially influence the boron diffusion during a subsequent rapid thermal annealing. It appears, therefore, that this original idea, already presented in another work, is of limited interest from a technological point of view.

A method of patterning single crystal GaAs based on ion implantation induced selective area exfoliation is suggested. Samples were implanted with 200–500 keV helium ions to a fluence range of 2–4×1016 He+/cm2 at room temperature through masks of Ni mesh (40 μm opening) or stainless steel wire (50 μm in diameter), and subsequent rapid thermal annealing at 350–500□ resulted in expulsion of ion beam exposed material. The influences of ion energy, ion fluence, implantation temperature, subsequent annealing conditions (temperature and ramp rate), and mask pattern and its orientation with GaAs lattice on the patterned exfoliation were examined.

Ge nanocrystals were produced in 4H–SiC by implantation of 250 keV Ge+ ions with a dose of 1×1016 cm−2 and subsequent rapid thermal annealing at 1400–1600 °C. Radiation damage and Ge distribution after implantation and annealing were analyzed by Rutherford backscattering spectrometry, cross-sectional transmission electron microscopy methods, and x-ray diffraction. After ion implantation a significant amount of Ge is incorporated into the SiC lattice and Ge nanocrystallites were not found. Thermal annealing leads to a local Ge redistribution and both Ge-rich and Ge nanocrystals are detected after annealing. The size of the nanocrystals varies between 2 and 10 nm.

In this paper, boron transient enhanced diffusion in silicon pre-amorphization implant (PAI) and carbon co-implant PAI is investigated via kinetic Monte Carlo approach. The damages induced by Si-PAI and carbon co-implant are calculated. Boron implantation and subsequent annealing are thereafter performed. The simulation implies that carbon co-implant PAI reduces the amount of interstitial near the surface when compared with Si-PAI and that carbon co-implant with silicon PAI reduced TED effectively.

We have studied the influence of the temperature of implantation on the morphology of the defects created during 1-MeV implantation of Si into GaAs, using RBS-channeling and TEM. The annealing behavior of the disorder has also been investigated.Implantation at liquid-nitrogen temperature results in the amorphization of the implanted sample for doses of 2×1014 cm−2 and larger. Subsequent rapid thermal annealing at 900°C for 10 seconds leads to partial epitaxial regrowth of the amorphous layer. Depending on the implantation dose, the regrowth can proceed from both the front and back ends of the amorphous region or only from the deep end of the implanted zone. Nucleation and growth of a polycrystalline phase occurs concurrently, limiting the extent of the epitaxial regrowth. After implantation at room temperature and above, two distinct types of residual defects are observed or inferred: point defect complexes and dislocation loops. Most of the point defects disappear after rapid thermal annealing at temperatures ≥ 700°C. The effect of annealing on the dislocation loops depends on the distance from the surface of the sample. Those in the near surface region disappear upon rapid thermal annealing at 700°C, whereas the loops located deeper in the sample grow in size and begin to anneal out only at temperatures in excess of 900°C. Implantation at temperatures of 200 - 300°C results in a large reduction in the number of residual point defects. Subsequent annealing at 900°C leads to a nearly defect-free surface region and, underneath that, a buried band of partial dislocation loops similar to those observed in the samples implanted at room temperature and subsequently annealed.

Nanolaminate Mn+1AXnphases (short MAX) are materials, that show interesting properties [1]. They exhibit high hardness as well as good thermal and chemical stability, which is commonly a ceramic like behavior. On the other hand, they are good conducting materials in the range of metals. MAX phases are a class of ternary carbides and nitrides, where M is an early transition metal, A is an element belonging to the groups IIIA to VA and X is either carbon or nitrogen. One of their properties which is similar to a ceramic material is their good chemical stability and therefore, they are very well suitable as corrosion protective coating. Up till now the corrosion behavior was investigated for bulk materials in different corrosive media [2] or at elevated temperatures [3,4]. Nevertheless, there is still an ongoing discussion about the mechanisms behind the corrosion protective properties. In most of the cases it is attributed to the crystalline structure of these materials. MAX phases show a hexagonal structures build of MX-octahedrons with intermediate A-element layers between them. Some attribute the corrosion protection properties to the passivation of the A element others to the passivation of the M element. In the presented work, the focus lies on the investigation of the corrosion protective properties of MAX phase thin films. Therefore, multilayer thin films of the three elements were deposited onto the substrates using PVD magnetron sputtering. The formation of the MAX phase was achieved using a subsequent rapid thermal annealing [5,6]. Afterwards the anodic behavior of the deposits was investigated electrochemically in 1M HCl and H2SO4 electrolytes. A good stability of the films in this media could be shown. To prove the self-healing behavior of this thin films, the deposits where mechanically scratched and afterwards annealed at 1000°C in air. A healing of the films could be shown attributed to the formation of oxides during the annealing. All obtained properties show that MAX phases are very well suitable as corrosion protective coatings in aggressive medias and damage can be repaired taking advantage of the self-healing properties of the films. [1] M.W. Barsoum, The MN+1AXN phases: A new class of solids, Prog. Solid State Chem. 28 (2000) 201–281. [2] V.D. Jovic, B.M. Jovic, S. Gupta, T. El-Raghy, M.W. Barsoum, Corrosion behavior of select MAX phases in NaOH, HCl and H2SO4, Corros. Sci. 48 (2006) 4274–4282. [3] Z.J. Lin, M.S. Li, J.Y. Wang, Y.C. Zhou, High-temperature oxidation and hot corrosion of Cr2AlC, Acta Mater. 55 (2007) 6182–6191. [4] J. Xie, X. Wang, A. Li, F. Li, Y. Zhou, Corrosion behavior of selected Mn+1AXn phases in hot concentrated HCl solution: Effect of A element and MX layer, Corros. Sci. 60 (2012) 129–135. [5] M. Hopfeld, R. Grieseler, T. Kups, M. Wilke, P. Schaaf, Thin Film Synthesis of Ti3SiC2 by Rapid Thermal Processing of Magnetron-Sputtered Ti-C-Si Multilayer Systems, Adv. Eng. Mater. 15 (2013) 269–275. [6] R. Grieseler, T. Kups, M. Wilke, M. Hopfeld, P. Schaaf, Formation of Ti2AlN nanolaminate films by multilayer-deposition and subsequent rapid thermal annealing, Mater. Lett. 82 (2012) 74–77.

Boron atoms are incorporated into (100)Si wafers by heating the substrates at 800 °C for 30 min in a (B2H6+H2) atmosphere and by subsequent rapid thermal annealing above 900 °C. Atomic and carrier-concentration profiles of boron-doped layers have been examined by a secondary-ion mass spectrometry and by differential Hall measurements, respectively. Experimental results have clearly shown that ultrashallow p+ layers, 300 Å thick, with a surface carrier concentration of 7.26×1019/cm3 can be formed by diffusion of boron at 800 °C and by subsequent RTA at 100 °C.

ZnSe nanocrystals have been synthesized in the silicon dioxide matrix by ion implantation of Zn+ and Se+ ions at 25 and 550 °C with subsequent rapid thermal annealing at 1000 °C for 3 min. Structural and optical properties of implanted films were analyzed using Rutherford backscattering spectrometry, transmission electron microscopy, Raman spectroscopy, and photoluminescence. It was shown that the temperature of implantation, as well as thermal treatment, affects the structural and optical properties of implanted films. In the case of high-temperature implantation, ZnSe nanocrystals have been formed already during the implantation process. In the case of room-temperature implanted samples, ZnSe nanocrystals have been synthesized only after subsequent rapid thermal annealing. It was found that implanted silica layers exhibit photoluminescence in wide visible spectral range. The origin of photoluminescence of the as-implanted and annealed silica samples is discussed.

Ion implantation induced intermixing of GaAs/AlGaAs and InGaAs/AlGaAs quantum wells was studied using low temperature photoluminescence. Large energy shifts were observed with proton implantation and subsequent rapid thermal annealing. Energy shifts were found to be linear as a function of dose for doses as high as ∼5×1016 cm−2. Proton implantation and subsequent rapid thermal annealing was used to tune the emission wavelength of InGaAs quantum well lasers as well as detection wavelength of GaAs/AlGaAs quantum well infrared photodetectors (QWIPs). Emission wavelength of lasers showed blue shift whereas detection wavelength of QWIPs was red shifted with intermixing.