Sb Ion Implantation Research Articles

Synergetic effect of Sb ion implantation on the optical and structural properties of single crystal rutile TiO2 (110)

The present study investigates the synergetic influence of Sb ion implantation on the optical and structural properties of single crystal rutile TiO2 (110). The Implantation was carried out at various fluences using 2 MeV Sb ions. X-ray diffraction, X-ray photoelectron spectroscopy, and Photoluminescence studies reveal the occurrence of an ion-induced annealing process which is remarkably responsible for the healing of defect states in the absence of any thermal treatment. Surprisingly, the ion-induced annealing appears to get activated only for the fluences of 1 × 1015 ions/cm2 and higher. At the fluence of 5 × 1015 ions/cm2, reduction in defect states, increase in crystallinity, increase in the photo absorption response (130 % in visible and 165 % in ultraviolet range), improved band-edge luminescence, and bandgap reduction (by ∼0.26 eV) is observed. The ion-induced annealing process effectively improves photo absorption properties without any thermal treatment. These results can play a pivotal role in photocatalysis applications.

Disorder and cavity evolution in single-crystalline Ge during implantation of Sb ions monitored in-situ by spectroscopic ellipsometry

Ion implantation has been a key technology for the controlled surface modification of materials in microelectronics and generally, for tribology, biocompatibility, corrosion resistance and many more. To form shallow junctions in Ge is a challenging task. In this work the formation and accumulation of shallow damage profiles was studied by in-situ spectroscopic ellipsometry (SE) for the accurate tracking and evaluation of void and damage fractions in crystalline Ge during implantation of 200-keV Sb + ions with a total fluence up to 1016 cm−2 and an ion flux of 2.1 × 1012 cm−2s−1. The consecutive stages of damage accumulation were identified using optical multi-layer models with quantitative parameters of the thickness of modified layers as well as the volume fractions of amorphized material and voids. The effective size of damaged zones formed from ion tracks initiated by individual bombarding ions can be estimated by numerical simulation compared with the dynamics of damage profiles measured by ion beam analysis and ellipsometry. According to our observations, the formation of initial partial disorder was followed by complete amorphization and void formation occurring at the fluence of about 1 × 1015 cm−2, leading to a high volume fraction of voids and a modified layer thickness of ≈200 nm by the end of the irradiation process. This agrees with the results of numerical simulations and complementary scanning electron microscopy (SEM) measurements. In addition, we found a quasi-periodic time dependent behavior of amorphization and void formation represented by alternating accelerations and decelerations of different reorganization processes, respectively. For the understanding and prevention of adverse void formation and for controlled evolution of subsurface nanocavities or cellular surface texture the in-situ monitoring of the dynamics of structural damage accumulation by the developed SE method is essential.

3D Simulation for Melt Laser Anneal Integration in FinFET’s Contact

Process integration feasibility of UV nanosecond melt laser annealing (MLA) in 14 nm node generation FinFET's contact for dopant surface segregation and activation is assessed by using a 3D TCAD simulation tool. In a n-type source/drain (S/D) in-situ phosphorous doped epilayer, Sb ion implantation is performed, considering the advantage of its surface segregation in lowering of the contact resistivity. The simulation results show that the heat sources created by the laser irradiation are confined mainly in the replacement metal gate (RMG) part, suggesting a potential interest of controlling the polarization of laser light to enlarge the process window by reducing the laser absorption in the RMG part. Also, the estimated solidification front velocity (V) in the MLA-induced epilayer regrowth (~4 m/s) satisfies the requirements (~1 m/s <; V <; ~15 m/s) to enable the surface segregation and metastable activation of the dopants. The surface segregation is also experimentally confirmed in the FinFET contact module.

Enhancement of gas sensing by implantation of Sb-ions in SnO2 nanowires

We describe gas sensing improvements of SnO2 nanowire (NW) gas sensors by Sb-ion implantation. SnO2 NWs were grown through a vapor-liquid-solid growth technique and Sb-ion implantation was performed by an ion implanter at different doses of 2 × 1013, 2 × 1014, and 2 × 1015 ion/cm2. The morphology and chemical compositions were confirmed by different characterization techniques. Gas sensing results demonstrated the gas sensing improvement by Sb-implantation, where the lowest dose gas sensor showed the best performance towards tested gases. However, high doses led to a reduced sensing response. We suggested the related sensing mechanism based not only on change of electron concentration by substituting Sn4+ ions to Sb+5 ions, but also on generation of surface defects. This study can open new possibilities to use ion-implantation as promising way to enhance the sensing capability of different gas sensors.

Oxygen gettering in low‐energy arsenic or antimony ion implanted Cz‐silicon

AbstractLow energy As or Sb ion implantation followed by furnace annealing was used to create ultra shallow junctions. It was found that a significant amount of oxygen was redistributed from the Si bulk to the As implanted layer leading even to an increase of the screening oxide film thickness. Using a marker layer created by implantation of 18O ions, it was confirmed that a large number of interstitial oxygen atoms are transferred from the bulk of the Si wafer to the wafer surface during implanted As activation annealing. Estimation of the O diffusivity in Si during the 950 °C activation anneal, yields a value of about 10–10 cm2 /s which is more than an order of magnitude larger than the literature value which is close to 7 × 10–12 cm2/s. In the case of Sb implantation, the oxygen gettering effect is much reduced. This difference in oxygen behavior can be attributed to the influence of mechanical stress in the near surface highly doped layer. The configuration of the mechanical stress field is different for the cases of As and Sb implantation, with tensile stress dominating for the latter. (© 2014 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Effect of swirl‐like resistivity striations in n+‐type Sb doped Si wafers on the properties of Ag/porous silicon SERS substrates

AbstractPorous silicon (PS) represents the prospective template for the fabrication of metal/PS nanostructures. However n+‐type Sb doped Si Czochralski wafers widely used to fabricate PS may contain resistivity striations and as‐grown microdefects with specific spiral distribution which influence Si dissolution during the formation of PS by anodizing. This may strongly affect on the PS microstructure and repeatability of metal/PS properties causing an increase of risk of a device failure. In the present research we studied the morphology and SERS‐activity of Ag/PS nanostructures formed by Ag immersion deposition on PS. SEM investigation revealed unequal distribution of pore diameters in the surface regions of PS which corresponds to spiral swirl‐like distribution of resistivity revealed in Si wafer by anodizing. Morphological changes of Ag deposit on spiral areas were found to cause decreasing of intensity of SERS signal. Additional implantation of Sb ions followed by high temperature annealing has shown to be a technique to improve homogeneity of Ag/PS SERS substrates. (© 2013 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Constraints on micro-Raman strain metrology for highly doped strained Si materials

Ultraviolet (UV), low penetration depth, micro-Raman spectroscopy, and high-resolution x-ray diffraction (HRXRD) are utilized as complementary, independent stress characterization tools for a range of strained Si samples doped by low energy (2keV) Sb ion implantation. Following dopant implantation, good agreement is found between the magnitudes of strain measured by the two techniques. However, following dopant activation by annealing, strain relaxation is detected by HRXRD but not by micro-Raman. This discrepancy mainly arises from an anomalous redshift in the Si Raman peak position originating from the high levels of doping achieved in the samples. This has serious implications for the use of micro-Raman spectroscopy for strain characterization of highly doped strained Si complementary metal-oxide semiconductor devices and structures therein. We find a direct correlation between the Si Raman shift and peak carrier concentration measured by the differential Hall technique, which indicates that UV micro-Raman may become a useful tool for nondestructive dopant characterization for ultrashallow junctions in these Si-based materials.

Raman Scattering Studies of InP Nanostructures Created by MeV Sb Ion Implantation

We have investigated the nanostructures created via MeV implantations by utilizing the techniques of Raman scattering and scanning probe microscope (SPM). SPM demonstrates that a large number of nanostructures are smaller than 100 nm in size and lower than 4 nm in height. SPM and Raman scattering techniques have been combined to show that although InP surfaces initially become rougher with increasing fluence, they become smoother after critical fluence when the crystalline/amorphous phase transition takes place. Raman spectroscopy further suggests an increase in tensile stress on the InP surface with increasing ion fluences. Phonon confinement model (PCM) has been applied to investigate the correlation length of the crystalline nano-zones in the InP lattice. Results indicate that crystalline nano-zones of 35 A may be embedded in the InP lattice at high fluences.

Formation and structure of Sn and Sb nanoclusters in thin SiO 2 films

We investigated the formation mechanism of Sn and Sb nanoclusters in thin SiO 2 films by X-ray absorption spectroscopy (XAS). Sn and Sb nanoclusters have been formed in 85 and 22 nm thick SiO 2 layers, respectively, by 80 keV/1×10 16 cm −2 Sn and 10 keV/5×10 15 cm −2 Sb ion implantation followed by thermal treatments. XAS analyses provided unique information on the local environment of Sn and Sb ions in SiO 2 with respect to different annealing conditions. Sn and Sb atoms are mainly coordinated with oxygen in the as-implanted samples. Annealing at different temperatures (800–1100 °C) and in different atmospheres (N 2 or Ar+7%H 2) leads to the formation of metallic clusters or oxidized ones. Even when the metallic phase is detected, a fraction of Sn or Sb atoms still remains dissolved in the matrix or forms small oxide clusters. Annealings at high temperature (1100 °C) for a short time (30 s) or in Ar+7%H 2 atmosphere (even if at lower temperature) are more effective for the formation of metallic clusters and for reducing the oxidized atom percentage in the matrix.

Ag : Sb and Sb : Ag implantations into high purity silica

Silica composites containing nanometer dimension colloids have been fabricated by implantation of Ag ions followed by Sb ions, and by implantation of Sb ions followed by Ag ions. Doses for the sequential element implantations were in ratios of 9 : 3 Ag : Sb and 3 : 9 Sb : Ag with the total dose held constant at 12 × 1016 ions/cm2. Energies of implantation were 305 keV for the Ag ions and 320 keV for the Sb ions. Single element colloids were also fabricated by implantation of Ag or Sb using the same nominal dose and implantation energy of the sequential implantations. Approximately spherical particles were formed in all implanted samples. Microstructures of the nanoclusters in the various samples were markedly different. Selected area diffraction techniques revealed that alloyed phases of Ag–Sb were formed in some of the sequential implantations. The microstructure and the optical response of the nanocluster glass composites were found to be strongly dependent upon the order of the ion species implanted. The optical spectra of the 3 : 9 Sb : Ag sample displays two resonance peaks indicative of a Ag resonance peak and a resonance peak of an alloyed phase of Ag–Sb. Optical spectra for the 9 : 3 Ag : Sb sample displays two broad absorption peaks indicative of coated particles.

Antimony implantation into Si-B doping superlattices—damage and enhanced diffusion

The influence of a heavy Sb ion implantation and subsequent annealing cycles in the temperature range of 800–1000 °C on B-delta doping superlattices in silicon layers grown by molecular beam epitaxy (MBE) was analyzed. Secondary ion mass spectroscopy (SIMS) measurements of these structures are used to investigate the generation and diffusion of point defects. The enhanced diffusion of B from the delta doping spikes in as grown and Sb implanted layers was theoretically described by solving the diffusion equation using the point defect model of TSUPREM−4 for different initial point defect distributions. To fit the experimental SIMS profiles the positively charged B-interstitial diffusion coefficient was changed from the default value of D=0.68 cm2/s to D=0.45 cm2/s. It was found that the given MBE growth process produces interstitials and vacancies with an almost constant average value of about 5×1016 cm−3. The Sb-implanted B modulation doped superlattice allows us to obtain a depth profile of the defect concentration. Assuming an overlapping of a constant value of 5×1016 cm−3 for interstitials and vacancies caused by the MBE growth with a distribution coming out of a damage calculation during Sb implantation, consisting of a flat high concentration region with an exponential decrease towards the level of the MBE layer, the main features of the B diffusion profile in the superlattice could be fitted. Thus, a simple initial point defect distribution model after implantation was able to explain the experimental situation.

N-Type doping of SnO2 thin films by Sb ion implantation

The effects of Sb implantation into textured thin films of SnO2 prepared by RF sputtering have been characterised by a range of techniques including secondary ion mass spectrometry (SIMS), X-ray and ultraviolet photoelectron spectroscopies (XPS and UPS), infrared reflectance, X-ray diffraction and conductivity measurements. The depth distribution of implanted 121Sb ions at low dose is characterised by a truncated bell-shaped distribution, with mean implantation ranges of 250 A for 90 keV implantation and 370 A for 150 keV implantation. However, owing to surface sputtering, the maximum in the implantation profile shifts toward the surface with increasing ion dose and for 90 keV ions at doses above 3 × 1016 cm–2, the implantation profile is sputter limited with maximum implant concentration at the surface. Electrical activation of the implanted ions is achieved at temperatures lower than those required to cause complete sintering of the small grains of the as-deposited films. The surface concentration of Sb seen in XPS increases during post-annealing treatments for Sb doses up to 3 × 10l5cm–2, but decreases at the higher dose of 3 × 1016 cm –2. These observations are discussed in terms of Sb segregation and Sb4O6 evaporation during the post-annealing treatment. The effects of Sb in introducing carriers into the surface region are investigated both by conductivity measurements and by UPS. The latter technique reveals directly occupation of Sn 5s conduction band states. Sb-implanted SnO2 thin films can be used as sensors for detection of methane at much lower temperatures than is possible with undoped films.

Observation of conduction electrons in Sb-implanted SnO 2 by ultraviolet photoemission spectroscopy

Conduction electrons introduced by 90 keV Sb ion implantation into SnO 2 thin films have been observed in photoemission spectra excited with He(I) ( hv = 21.1 eV) radiation. The carrier concentration is smaller than expected from the surface Sb concentration seen in XPS. This is discussed in terms of trapping of electrons in Sb(III)-like lone pair states associated with surface Sb ions.

Observation of conduction electrons in Sb-implanted SnO2 by ultraviolet photoemission spectroscopy

Conduction electrons introduced by 90 keV Sb ion implantation into SnO2 thin films have been observed in photoemission spectra excited with He(I) (hv = 21.2 eV) radiation. The carrier concentration is smaller than expected from the surface Sb concentration seen in XPS. This is discussed in terms of trapping of electrons in Sb(III)-like lone pair states associated with surface Sb ions.

Magnetoreflection studies of ion implanted bismuth

The effect of the implantation of Sb ions on the electronic structure of the semimetal bismuth is studied by the magnetoreflection technique. The results show long electronic mean free paths and large implantation-induced increases in the band overlap and L-point band gap. These effects are opposite to those observed for Bi chemically doped with Sb.