Semiconductor Nanostructures

This research was funded by, and implemented within, a UK national research organisation, while the author was the KE and Impact Evaluation Manager responsible for assessing impact on a £15m UK government-funded research programme.

This work was also submitted as the authors MBA dissertation which was accepted and awarded in 2009.

ABSTRACT: A methodology and methods ‘toolbox’ is proposed for conducting impact research and assessment from within research programmes. The emphasis is upon how to clarify and assess the wider impacts from the early stages onwards.

The approach explicitly acknowledges, and attempts to address, the known issues and challenges of impact assessment while drawing upon the resources and opportunities available to research managers and researchers within such programmes.

The study has two triangulating foundations. Firstly, it examines the academic literature to help identify and design the pilot methodology and methods. Secondly it trials these in a real programme to both test and improve them.

The study was conducted over one year within one leading UK research organisation, where two research programmes (and around 60 research projects of £15m total value) were being assessed for their impacts. The study draws upon actual impact management experience and reflection, prospective (ex ante) and retrospective (ex post) assessments, participatory contributions from leading researchers undergoing assessment, and consultation with external users. The findings of this study outline the pilot and its first iteration. Recommendations are made for improvement to the methodology and methods.

A subsequent follow-on bid to UK government incorporating the impacts identified from implementing this methodology, successfully led to a further £15m of government funding.

It is expected the pilot methodology and methods will be applicable to other organisations, conducting and funding such research programmes, required to research and assess the wider research impacts.

Although primary focus of implemetation trials was upon research in physical sciences, technology, high-tech engineering, computing/IT, and environment, the wider literature study, the methodology design and justification, the methods proposed and used, and the resulting general recommendations and lessons are expected to apply more broadly to many other research areas, where the impact is to be found more widely in the society, economy, government or public sector or within organizations, policies, professions or the public.

Interest in this work is expected from research programme managers, impact managers and assessors, management consultants advising in this area, and government funding managers, all seeking to embed a developing approach to understand, capture, and enhance wider impact.

Anatase TiO2 displaying dual morphologies were synthesized with a simple chemical route via a single step. A strong correlation between the dye sensitized solar cell (DSSC) device performance and the obtained dual morphologies are highlighted using relevant evidences from UV-vis and diffuse reflectance spectroscopy (DRS), Raman analysis, field emission scanning electron microscope, high resolution transmission electron microscope, current-voltage characteristics and impedance analysis. Structural investigation revealed that the interested medium in this work employed for the synthesis of TiO2 produced different types of dual morphologies such as nanospheres with nanoparticles (NSNP), microsphere decorated with nanoparticles (μSNP) and nanoparticles with stone like features (NPS). UV-vis and DRS results indicated the ability of the materials to assist with diffused reflectance and optical absorption of the screen printed photoanodes. In addition, an investigation of Raman vibrational characteristics was carried out in detail using synchronous and asynchronous 2D correlation analysis. The high intense Eg anatase mode of Raman spectrum was simulated using a phonon confinement model and its normalised spectra are compared with an experimental data. The resultant performances in the DSSCs were not indicative by the material properties; so, the charge transfer resistance (Rct) and recombination properties of the photoanode were investigated. These results showed that the Nyquist plot of NSNP possesses the smallest diameter, which reveals that the device based on NSNP offers the lowest Rct value that accounts for the higher conversion efficiencies when compared with the DSSC device based on photoanodes μSNP and NSP. It can be concluded that the improved power conversion efficiency shown by photoanode fabricated using NSNP has the dual role of optimum surface area for dye loading and light scattering centres. These properties, when optimized along with the offered pathway for electrolyte diffusion to the dye degeneration with less Rct, could lead to better photoelectric conversion efficiency.

Cadmium sulfide (CdS) and cadmium telluride (CdTe) are two leading semiconductor materials used in the fabrication of thin film solar cells of relatively high power conversion efficiency and low manufacturing cost. Numerical simulations of current-voltage characteristics of thin film CdS/CdTe solar cell and nanowire CdS/CdTe solar cell were performed as a function of temperature using SCAPS-1D to demonstrate the fact that use of CdS nanowires enhances the efficiency of the CdS/CdTe solar cells. For the simulation of nanowire CdS/CdTe solar cell we changed some parameters (thickness, bandgap, electron and hole mobility) of the simulation of thin film CdS/CdTe solar cell. The Optical properties (absorption and scattering cross section) of CdS nanowire were observed to determine the preferable diameter for CdS nanowires. Simulations for realizing the absorption and scattering cross sections for various diameters of CdS nanowire were done using Lumerical FDTD solutions. From simulation results it was evident that nanowire CdS design was superior to planar CdS film due to enhanced performance in the CdS/CdTe solar cell through higher open circuit voltage and higher efficiency as for thin film CdS/CdTe solar cell the open circuit voltage was 0.6908V and efficiency was 14.15%. For nanowire CdS/CdTe solar cell model the open circuit voltage was 0.7889V and efficiency was 15.07%. Device parameters such as: thickness, bandgap, interface state density, density of states, electron and hole mobility, trap density, metal work function, temperature, parasitic series and shunt resistance were studied which can affect the efficiency of the nanowire-CdS/CdTe solar cell. The rollover effect on nanowire CdS/CdTe solar cell was explained by varying the majority carrier barrier height of back contact from 0.4 to 0.7 eV. It proves that change of barrier height at the contact can cause rollover effect. The crossover effect was observed by varying the thickness of CdS nanowire layer and removing defect of i-SnO2 layer. It was evident that the removal of defect in i-SnO2 is responsible for producing the crossover effect. Though SCAPS-1D is basically designed for simulation of thin film solar cells, it can be concluded that SCAPS-1D can also provide realistic simulation for nanowire CdS/CdTe solar cells.

In order to interpret the electrical characteristics of fabricated Au/ZnO/n-Si structures as a function of frequency and voltage well, their capacitance– voltage (C–V) and conductance–voltage (G/x–V) measurements were carried out in a wide range of frequencies (0.7 kHz–2 MHz) and voltages (± 6 V) by 50 mV steps at room temperature. Both the C–V and G/x–V plots have reverse, depletion, and accumulation regions such as a metal–insulator/oxide semiconductor (MIS or MOS) structures. The values of doped-donor atoms (N D), Fermi energy level (E F), barrier height (U B), and series resistance (R s) of the structure were obtained as a function of frequency and voltage. While the value of N D decreases with increasing frequency almost as exponentially, the value of depletion width (W D) increases. The values of C and G/x increase with decreasing frequency because the surface states (N ss) are able to follow the alternating current (AC) signal, resulting in excess capacitance (C ex) and conductance (G ex /x), which depends on their relaxation time and the frequency of the AC signal. The voltage-dependent profiles of N ss were obtained from both the high–low frequency capacitance and Hill-Colleman methods. The other important parameter R s of the structure was also obtained from the Nicollian and Brews methods as a function of voltage.

The need for tighter control over film uniformity, conformality, and properties at decreasing thicknesses was met by a gradual evolution from physical vapor deposition (PVD), to chemical vapor deposition (CVD), and eventually atomic layer deposition (ALD) processes.  Of all manufacturing-worthy thin-film deposition processes, ALD has the greatest potential to satisfy these requirements.  However, the intrinsic constraints of recurrent two atom reactivity and associated byproducts have kindled tremendous interest in other self-limiting deposition processes such as Molecular Layer Deposition (MLD), Self-Assembled Monolayer (SAM), and “Click” Chemistry Deposition (CCD)  processes, either as alternatives to or in conjunction with ALD.  This overview provides definitions, illustrations and examples of these processes.

Vanadium pentoxide (V2O5) thin films were deposited on glass substrates using spray pyrolysis technique. Aqueous solution of ammonium vanadate with 0.1 M concentration was used to deposit V2O5 thin films at different substrate temperatures. The structural, morphological, electrical, optical and vapour sensing properties of the films were investigated. XRD patterns confirmed the polycrystalline nature of the films with orthorhombic structure. Crystallite size was increased with an increase in the substrate temperature. SEM images showed the formation of films with flower like morphology. From the optical absorbance spectra, the optical band gap was determined and varied between 3.34 to 3.24 eV. The charge carrier concentration was found to be increased with substrate temperature. Room temperature xylene sensing characteristics of the films were investigated. The influence of substrate temperature on the vapour sensing characteristics of V2O5 is reported.

Au/graphene oxide (GO)-doped PrBaCoO nanoceramic/n-Si capacitors were fabricated and their admittance measurements were carried out between 1 kHz and 1 MHz at room temperature. Experimental results showed that the capacitance (C) and conductance (G/w) values are strong functions of frequency and applied bias voltage. C–V plot revealed two distinctive peaks at low frequencies which are located at about 0 and 2 V, such that the first peak disappears towards high frequencies. The energy density distribution profile of the interface/surface states (D it / N ss) and their relaxation time (s) and capture cross section (r p) of the sample were obtained by using the admittance method. In addition, the voltage-dependent profile of N ss and resistance were obtained by using low–high frequency capacitance and Nicollian-Brews method, respectively, and they also reveal two distinctive peaks, respectively. Two peaks' behavior in the forward bias C–V, N ss –V and R i –V plots confirmed the existence of two different localized regions of N ss between Si and interfacial layer. The series resistance (R s) of the device decreased with increasing frequency from 175 X at 1 kHz to 72 X at 1 MHz. As a result, the mean value of D it was found about 5 9 10 13 eV-1 cm-2 which is reasonable for an electronic device.

The dielectric properties of Au/(1 % graphene
doped-Ca1.9Pr0.1Co4Ox)/n-Si structures were investigated
by the impedance spectroscopy method including capacitance–
voltage (C–V) and conductance–voltage (G/x–
V) measurements in the frequency range of 10–2 MHz at
room temperature. The experimental results show that the
real and imaginary parts of dielectric constant (e0, e00) and
electric modulus (M0 andM00), and ac electrical conductivity
(rac) are a strong functions of frequency and voltage, both.
Negative dielectric constant behavior was observed at sufficiently
high forward bias voltages at low frequencies and it
was attributed to the interfacial polarization, interface traps
and series resistance. e0 decreases with increasing frequency
at sufficiently high biases whereas e00 increases. Since
interfacial polarization and interface states, both, can follow
the ac external signal easily at low frequencies, there occurs
a contribution to the measured capacitance and conductance.
The negative values of e0 correspond to maximum value of
e00. Such contrary behavior in the e0 and e00 appears as an
abnormality when compared to the conventional behavior
metal–semiconductor structures with and without interfacial
layer. Experimental results confirmed that the dielectric
properties of these structures are quite sensitive to the frequency and applied bias voltage, both, especially at low
frequencies and high voltages because of density distribution
of interface states and interfacial polarization.

In this study, the dielectric properties and alternating-current (ac) conductivity of Au/(PVA/Ni,Zn acetates)/n-Si Schottky diodes (SDs) were determined by the measurement impedance technique. Dielectric properties and electrical conductivity of Au/(PVA/Ni,Zn acetates)/n-Si SDs in the frequency range of 0.5 kHz to 10 MHz and voltage range of −2 to 5 V were investigated in detail using experimental C–V and G–V measurements. Experimental results show that the values of the dielectric constant (ε′), dielectric loss (ε″), and tan δ obtained from the measured capacitance and conductance have been a strong function of frequency and applied voltage, and the values of ε′ have been unexpectedly found to be negative, especially at high voltages. Other parameters of Au/(PVA/Ni,Zn acetates)/n-Si SDs, such as ac electrical conductivity (σac), the real part of electric modulus (M′), and the imaginary part of electric modulus (M″) varied with changing frequency for various voltages. The main propose of this study is to discuss the polymeric interfacial layer at metal and semiconductor affect and probe the dielectric properties of Au/(PVA/Ni,Zn acetates)/n-Si SDs regarding the negative capacitance as a function of frequency and voltage. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

In order to compare the main electrical parameters such as ideality factor (nn), barrier height (BH) (ΦI–VΦI–V), series (RsRs) and shunt (RshRsh) resistances and energy density distribution profile of surface states (NssNss), the Au/nn-Si (MS) Schotthy diodes (SDs), with and without interfacial (Ca1.91.9Pr0.10.1Co4Oxx) layer were obtained from the current–voltage (II–VV) measurements at room temperature. The other few electrical parameters such as Fermi energy level (EFEF), BH (ΦC–VΦC–V), RsRs and voltage dependence of NssNss profile were also obtained from the capacitance–voltage (CC–VV) measurements. The voltage dependence of NssNss profile has two distinctive peaks in the depletion region for two diodes and they were attributed to a particular distribution of NssNss located at metal–semiconductor (MS) interface. All of these results have been investigated at room temperature and results have been compared with each other. Experimental results confirmed that interfacial (Ca1.91.9Pr0.10.1Co4Oxx) layer enhanced diode performance in terms of rectifier rate (RR=IF/IRIF/IR at ±3.4 V), NssNss (at 0.5 eV) and RshRsh (−3.4−3.4 V) with values of 265, 5.38×10135.38×1013eV−1⋅−1⋅cm−2−2 and 7.87×104Ω7.87×104Ω for MS type Schottky barrier diode and 2.56×1062.56×106, 1.15×10131.15×1013 eV−1⋅−1⋅cm−2−2 and 7.50×108Ω7.50×108Ω for metal–insulator–semiconductor (MIS) type SBD, respectively. It is clear that the rectifying ratio of MIS type SBD is about 9660 times greater than MS type SBD. The value of barrier height (BH) obtained from CC–VV data is higher than the forward bias II–VV data and it was attributed to the nature of measurements. These results confirmed that the interfacial (Ca1.91.9Pr0.10.1Co4Oxx) layer has considerably improved the performance of SD.

In this study, a new method to synthesize neodymium doped ceria ceramic nanopowders by the electrospinning of the hybrid polymers solution of their composite precursor was put forward. Calcined and sintered nanopowders were characterized by FT-IR, XRD, BET, SEM, and AFM techniques. According to the XRD analysis, the obtained powders are single phase and independent of the dopant concentration in the range investigated. The crystallite sizes were calculated using Scherrer equation. Moreover, lattice parameters, dislocation densities and microstrain values were calculated. BET results show that the increase of the neodymium doped content decrease the surface area of the composite powders, confirming the highly ordered micro and mesostructure. SEM and AFM results show that the samples have spherical grains. According to the surface roughness measurements, the increase in the amount of neodymium and the decrease in the amount of cerium decreased the surface roughness.

In order to see effects of interfacial (with and without different graphene (GP) + Ca1.9Pr0.1Co4Ox-doped PVA) layer on the electrical characteristics of conventional Au/n-Si (MS) contacts. Therefore, Au/(GP + Ca1.9Pr0.1Co4Ox-doped PVA)/n-Si (MPS) structures were fabricated with different rates of (%3 GP, %7 GP) PVA and were fabricated on same n-Si wafer. Au/n-Si (MS), Au/PVA/n-Si, Au/%3GP + Ca1.9Pr0.1Co4Ox-doped PVA/n-Si and Au/%7GP + Ca1.9Pr0.1Co4Ox-doped PVA/n-Si structures were fabricated and their main electrical characteristics compared each other by using current–voltage (I–V) methods. The forward and reverse bias current voltage (I–V) characteristics of with and without GP + Ca1.9Pr0.1Co4Ox-doped PVA/n-Si at room temperature were studied to investigate its main electrical parameters. The energy density distribution profile of the interface states (Nss) was obtained from the forward bias I–V data by taking into account voltage dependent ideality factor (n(v)) and effective barrier height (Φe) and they increase from at about mid-gap energy of Si to bottom of conductance band edge. In addition, voltage dependent profile of resistivity of the structure was obtained from I–V data for four different structures. The analysis of experimental results reveals that the existence of GP + Ca1.9Pr0.1Co4Ox-doped PVA interfacial layer improves the performance of MS structure. In order to determine the dominant current-transport mechanism (CTM) in the whole forward bias region of these structures, the double logarithmic forward bias I–V plots were also drawn. These plots exhibit two distinct linear region with different slopes which are corresponding to intermediate and high forward bias voltages. The slope of these plots show that in the region 1 (low biases) the dominant CTM is trap-charge-limited current (TCLC), whereas in the region 2 (high biases) is space-charge-limited current (SCLC) for four diodes.

We report the results of direct measurements and a theoretical investigation of the in-plane effective mass in the two-dimensional electron gas of nominally undoped AlGaN/GaN heterostructures with a different degree of quantum confinement. It is shown that in most cases the conduction band nonparabolicity effect is overestimated and the electron wave-function penetration into the barrier layer should be taken into account. The contribution of the wave-function hybridization is determined to play the dominant role. The band edge effective mass value is deduced to be (0.2+-0.01) m0.

In this review we describe some new approaches
in the surface photovoltage spectroscopy (SPS)
performed in the metal-insulator-semiconductor
operation mode, which are related to open questions
in the SPS characterization of nanostructures. The
first new approach is based on surface photovoltage
(SPV) phase spectroscopy. We show that i) the
sign of the bandgap-related knee in the spectrum of the SPV phase modulus is positive (negative)
for downward (upward) surface band bending and
ii) for the case of non-linear recombination, the
SPV phase spectrum reflects the features of
the optical absorption coefficient spectrum. We
demonstrate the necessity of simultaneous
examination of both amplitude and phase SPV
spectra in order to understand correctly the
experimental data. As a second original approach,
we have developed a vector model, in which the
SPV signal is represented by a radial vector,
containing all the information given by the
amplitude and phase SPV spectra. Further, after a
brief overview of the SPS characterization of
nanostructures in the last decade, we present the
results of our pioneering SPS studies of various
nanostructures with graded interfaces including
AlAs/GaAs superlattices with GaAs embedded
quantum wells, multilayer InAs/InP quantum
wires, InAs/InGaAlAs quantum dashes-in-well
laser structures and multilayer InP/GaAs type II
quantum dots. The interpretation of the amplitude
and phase SPV spectra is carried our by the
proposed vector model for the SPV signal in
parallel with the analysis of data obtained by other
experimental methods and electronic structure
calculations. As a result valuable information
about the investigated systems is obtained.

A synthetic method is presented for the production of isotetrasilane, a higher order perhydridosilane, with the purity and volume necessary for use in extensive studies of the chemical vapor deposition (CVD) of epitaxial silicon (e-Si) thin films.  The chemical characteristics, thermodynamic properties and epitaxial film growth of isotetrasilane are compared with those of other perhydridosilanes. A film-growth mechanism distinct from linear perhydrodosilanes H(SiH2)nH, where n is ≤4, is re-ported.  Preliminary findings are summarized for CVD of both unstrained e-Si and strained e-Si doped with germanium (Ge) and carbon (C) employing isotetrasilane as the source precursor at temperatures of 500-550C.  The results suggest that bis(trihydridosilyl)silylene is the likely deposition intermediate under processing conditions in which gas-phase depletion reactions are not observed.

In this paper, the potential distribution for symmetric double gate stack-oxide junctionless field effect transistor (DGS-JLFET) in subthreshold region has been observed. Using the potential distribution, current vs voltage (Ids vs. Vgs) characteristic and various short channel effects such as on-off ratio (Ion/Ioff), subthreshold swing (SS), drain induced barrier lowering (DIBL), threshold voltage roll-off (TVRO) have been studied by changing device parameters. It has been observed that, if the dielectric constant of high-k oxide is increased and the thickness of stack-oxide is decreased, device shows better short channel effect (SCE) performance in the most of the cases. Keywords— Double gate stack-oxide junctionless field effect transistor (DGS-JLFET), on current (Ion), off current (Ioff), on-off ratio (Ion/Ioff), subthreshold swing (SS), drain induced barrier lowering (DIBL), threshold voltage roll-off (TVRO), short channel effect (SCE).

Strong electrophilic natured acetaldehyde present in various food and beverages damages genetic material and induces diseases like atherosclerosis. Detection and quanti fi cation of such a carcinogen poses a major challenge. In this context, a novel room temperature acetaldehyde sensor made up of hierarchical ZnO nanostructures and prepared by a simple and template-free method has been reported. ZnO nanostructures were grown on glass substrates by a chemical spray pyrolysis technique at the substrate temperature of 523 K. Di ff erent nanostructures, namely tiny nanoplatelets, branched nanorods and thicker nanoplatelets, were formed by an annealing process. The crystal structures, morphologies and optical absorbances of the hierarchical ZnO nanostructures were investigated by X-ray di ff raction (XRD), field emission scanning electron microscopy (FE-SEM) and UV-vis spectrophotometry, respectively. The branched nanorods showed an excellent sensing response towards 20 to 500 ppm of acetaldehyde
vapour. The role of high density junctions of the branched ZnO architecture in enhancing the vapour sensing performance has been highlighted. The observed selectivity, range of detection and stability of the branched ZnO nanorods have proven their potential as a sensing element for the detection of acetaldehyde.

Infrared spectroscopy is used to compare the Si/SiO2 interfaces created by thermal oxidation of a standard Si(100) substrate and of an ordered, (1x1) Si(100) substrate. The thermal oxides (approximately 25 Angstrom) examined in this study are etched in dilute hydrofluoric acid and the resulting films analyzed spectroscopically. The behavior of the dominant optical phonon modes as a function of film thickness provides strong evidence that the ordered Si(100) substrate provides a template for an Si/SiO2 interface with a higher degree of homogeneity in the Si-O bonding environment of the intervening substoichiometric SiOx layer than does the standard Si(100) substrate. (C) 2004

Fabrication of ZnS thin films having similar stoichiometry at different substrate temperatures (TS) e.g. 200 C, 300 C and 400 C by means of RF magnetron sputtering method is presented. The films grown at TS of 200 C are in cubic zinc-blende phase and textured along (111) plane. The films deposited at TS of 300 C and 400 C are in hexagonal wurtzite phase. The surface roughness and grain size of the films increase with increasing TS. The ultra-violet and visible absorption studies show that the bandgap of films can be tailored by varying TS, taking advantage of the structural transformation.

Zinc sulfide (ZnS) thin films in zinc-blende (ZB) and wurtzite (W) phases have been fabricated by pulsed laser deposition. 150 MeV Ni ion beam irradiation has been carried out at different fluences ranging from 1011 to 1013 ions/cm2 at room temperature for ion induced modifications. Structural phase transformation in ZnS from W to ZB phase is observed after high energy ion irradiation which leads to the decrease in bandgap. Generation of high pressure and temperature by thermal spike during MeV ion irradiation along the ion trajectory in the films is responsible for the structural phase transformation.

Solar Energy is an everlasting source of energy with minimal carbon footprint. However, due to lack of reliability and consistency it needs to be converted into more reliable and effective means that can be used to provide energy on demand. Hydrogen is a promising carrier and is thus an efficient mean of energy to be converted in, stored and transported. A more direct approach towards harnessing Solar Energy is by photo-aided generation of hydrogen via splitting of water using photolysis. Photo-catalytic water splitting is therefore a promising method for future energy security. On the other hand, strain sensing is a useful technique to measure medium range loads in trusses or tension rods & can easily replace the existing fragile & expensive semiconductor based sensors. This was done by using a composite of TiO 2 /Reduced Graphene Oxide (RGO); TiO 2 (anatase) was synthesized via sol-gel process and the main precursor was titanium tetrapropoxide (TTIP). Titania (anatase) characterized by XRD and photo spectrometry while Graphene oxide was synthesized via modified Hummer's Method. The obtained Reduce Graphene Oxide was dispersed using Sodium Dodecyl Benzene (SDB) and Hydrazine Hydrate. A drastic synergetic effect was found by simply mixing RGO with TiO 2 Solution. This not only broadened the photo-activity spectrum of TiO 2 from UV region to the more available visible light radiation but also exhibit strain sensing properties and considerable tunable gauge factor. The photocatalytic effect of our composite was tested by coating it over Polycarbonate & then analyzing emitted gas bubbles in a UV radiation chamber while strain sensing was done by coating it on an elastic substrate & applying loads against values of resistance which were measured. This study will also include the reduction of recombination and band gap of TiO 2 in order to synchronize it with the available Solar Spectrum thus maximizing solar-to-hydrogen efficiency.

In this work, room temperature oxidation of GaAs was investigated using ion beam oxidation (mO). In lBO, an ion beam is used to introduce oxygen athermally into the substrate, in this case GaAs. GaAs bonds are broken upon collision with the ions, making gallium and arsenic atoms readily available to react with the oxygen species. Ion beam oxidation of GaAs at room temperature was studied as a function ofoxygen ion energy between 500 and is keY. The ion beam oxidized GaAs was characterized in situ by Auger electron spectroscopy (AES) and ex situ with x-ray photoelectron spectroscopy (XPS) for accurate determination of the film chemical composition. Below 1 keY, a thin oxide film is formed: it is composed of Ga20 3 and AS20 3 with almost no metallic arsenic, and presents insulating properties.
As the ion energy increases, preferential sputtering of As and decomposition of AS203 increase and prevent formation of an
insulating film. No damage was detected by Rutherford backscattering spectrometry (RES) combined with ion channeling, in the substrate subjected to IBO below 1 keV.""