bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication of ternary and quaternary chalcogenide compounds based on Cu, Zn, Sn and Si for thin film photovoltaic applications
Authors: Brammertz Guy , Vermang Bart , ElAnzeery Hossam , Sahayaraj Sylvester , Ranjbar Samaneh , Meuris Marc , Poortmans Jef
Published: April 2022

We investigated the use of ternary and quaternary chalcogenide compounds based on Cu, Zn, Sn and Si for use as high band gap absorber layers in thin film photovoltaics. We have investigated the fabrication of Cu2Zn(Sn,Si)Se4, Cu2Si(S,Se)3 and Cu8Si(S,Se)6 thin film layers. Whereas, Cu2Zn(Sn,Si)Se4 and Cu2Si(S,Se)3 appeared to be difficult to fabricate, because the Si did not intermix well with the rest of the elements at the typical process temperatures used for glass substrates, Cu2ZnSiSe4 and Cu8Si(S,Se)6 could be formed. The fabricated layers were polycrystalline with a typical thickness of about 1 μm. We also fabricated solar cells with the different absorber materials, using a standard Mo back contact and CdS/ZnO buffer layer combination, but despite very bright photoluminescence response of the Cu8SiS6 and Cu8SiSe6 layers at an energy of about 1.84 and 1.3 eV respectively, the measured efficiencies remained below 0.1% due to particularly low photocurrents.
Morphology of multiple‐selenized Cu2ZnSn(S,Se)4 absorber layers
Authors: Neuwirth Markus , Seeger Jasmin , Kalt Heinz , Hetterich Michael
Published: April 2022

The impact of multiple‐selenization of wet‐chemical precursors for kesterite‐type Cu2ZnSn(S,Se)4 solar cells is reported. The absorber forms a compact layer with mostly big grains. Gaps between the big grains are filled with smaller grains. Also the absorber lacks the common trilayer/multilayer structure. As a result the layer thickness is more homogeneous and the morphology is more evened out. This is the basis for a more homogeneous device parameter distribution across large samples and a better reproducibility of CZTSSe solar cells.
Effect of surface treatment by hydrogen peroxide solution on Cu2ZnSnS4 thin films
Authors: Miyazaki Hisashi , Aono Masami , Kishimura Hiroaki , Jimbo Kazuo , Katagiri Hironori
Published: April 2022

Cu2ZnSnS4 (CZTS) is one of the promising materials of absorber layer used in thin film solar cells. In this paper, we revealed the effects of surface treatment by hydrogen peroxide solution on the chemical and structural properties of CZTS thin films in order to improve the conversion efficiency. On the Raman spectra, the full width at half maximum (FWHM) of A1 peak at around 338 cm−1 is not affected by H2O2 solution treatment. However, Raman scattering spectroscopy results showed that the existence of not only CZTS but also oxide was confirmed by the H2O2 solution treatment. From the XPS spectra, Zn, and S were dissolved by H2O2 solution. The surface oxidation takes place in a very short period of time. The sulfate phase is existence on the CZTS surface by H2O2 surface treatment.
Electronic structure of Cu2ZnSn(SxSe1−x)4 surface and CdS/Cu2ZnSn(SxSe1−x)4 interface
Authors: Udaka Yusuke , Takaki Shin'ichi , Isowaki Keisuke , Nagai Takehiko , Kim Kang Min , Kim Shinho , Tampo Hitoshi , Shibata Hajime , Matsubara Koji , Niki Shigeru , Sakai Noriyuki , Kato Takuya , Sugimoto Hiroki , Terada Norio
Published: April 2022

Changes of the electronic structure of the Cu2ZnSn(SxSe1−x)4 [CZTSSe] films and the band alignment at the interfaces between CdS buffer and the CZTSSe in conjunction with the anion‐mixing ratio x = 0–1 have been investigated using in situ X‐ray, ultraviolet photoemission spectroscopy (XPS, UPS), and inverse photoemission spectroscopy (IPES). Changes of the UPS and IPES spectra in conjunction with x have revealed that the electronic structure of the CZTSSe surface is characterized with the preferential rise of conduction band minimum (CBM) in conjunction with the increase of x. As x increases, interface induced band bending decreases from 0.5 to 0.6 at the CdS/CZTSe (x = 0) interface to 0.1–0.2 at the CdS/CZTS (x = 1) one. And the downward shift of CBM due to the deposition of the CdS layer is enhanced as x increases. These changes result in the monotonous decrease of conduction band offset (CBO) in conjunction with the increase of x: CBO at the x = 0 and 1 interfaces are +0.5 and −0.14 to −0.15 eV, respectively. The values of CBO are consistent with the device properties; occasional emergence of double junction like current–voltage characteristics in the CdS/CZTSe‐based cells, serious voltage‐loss in the CdS/CZTS ones, and the highest performance achieved in the CdS/CZTSSe ones.
Optical and magnetic properties of some XMnSb and Co2YZ Compounds: ab initio calculations
Authors: Palaz Selami , Koc Husnu , Ozisik Haci , Deligoz Engin , Mamedov Amirullah M. , Ozbay Ekmel
Published: April 2022

In present work, our research is mainly focused on the electronic structures, optical, and magnetic properties of XMnSb (X = Ni, Cu, Pd), Co2YZ (Y = Ti; Z=Si, Ge, Sn), and Co2YZ (Y =Mn; Z=Al, Ga, Si) Heusler compounds by using ab initio calculations within the generalized gradient approximation. The calculations are performed by using the Vienna ab initio simulation package based on the density functional theory. The band structure of these Heusler alloys for majority spin and minority spin were calculated and the majority spin states cross the Fermi level and thus have the metallic character, while the minority spin states open the band gaps around the Fermi level and thus have the narrow‐band semiconducting nature. We also find that these Heusler compounds have the indirect band gaps in the minority spin channel. The real and imaginary parts of dielectric functions and hence the optical functions such as energy‐loss function, the effective number of valance electrons and the effective optical dielectric constant for XMnSb and Co2YZ compounds were also calculated. In addition, we also show the variations of the total magnetic moment per f.u. and minority spin gap width of these compounds with optimized lattice constants: minority spin gap width decreases with increasing the lattice constants.
Preparation of CuIn(S,Se)2 films by PLD of precursor layers and post‐annealing and their application to solar cells
Authors: Kawabe Toshiyuki , Maeda Tsuyoshi , Wada Takahiro
Published: April 2022

Cu‐In‐S precursor films were deposited at various substrate temperatures by pulsed laser deposition (PLD). CuIn(S,Se)2 films were prepared by post‐annealing the Cu‐In‐S precursor films in H2S and Se atmosphere. CuIn(S,Se)2 solar cells with a device structure of Au/ITO/i‐ZnO/CdS/CuIn(S,Se)2/Mo/soda‐lime (SLG) glass were fabricated and characterized. Higher conversion efficiency was obtained for the CuIn(S,Se)2 solar cell with the precursor film deposited at room temperature. The phase and microstructure of the Cu‐In‐S precursor and the annealed CuIn(S,Se)2 films were examined by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). We found that the quality of the CuIn(S,Se)2 films was strongly affected by the deposition temperature of Cu‐In‐S precursor films. We discuss the grain growth and sintering in CuIn(S,Se)2 films on the basis of the results of XRD and SEM. The highest conversion efficiency of 6.38% (Voc = 521 mV, Jsc = 22.6 mA cm−2, FF = 0.541) was obtained for the CuIn(S,Se)2 solar cell with the precursor film deposited at room temperature and post‐annealed at 620 °C. The solar cell was analyzed by secondary ion mass spectroscopy (SIMS) and transmission electron microscopy (TEM).
Cu2(Sn1−xGex)S3 solar cells prepared via co‐evaporation and annealing in germanium sulfide and sulfur vapor
Authors: Sasagawa Shohei , Yago Aimi , Kanai Ayaka , Araki Hideaki
Published: April 2022

Cu2Sn1−xGexS3 (CTGS) thin films were prepared by co‐evaporation of Cu, Sn, and S to form Cu2SnS3 (CTS) precursors, which were then annealed at 570 °C in an atmosphere composed of N2, GeS2, and S vapor. The films were then used to fabricate photovoltaic cells with the structure glass/Mo/CTGS/CdS/ZnO:Al/Al. A cell with a film composition of Cu2(Sn0.86Ge0.14)S3 fabricated from slightly Cu‐rich CTS (Cu/Sn = 2.07) exhibited a conversion efficiency of 3.4% and an open‐circuit voltage of 0.29 V. The band gap based on the external quantum efficiency was estimated to be approximately 1.0 eV. The open‐circuit voltage was found to be larger than that for a CTS thin film solar cell and increased with band gap energy.
Optical properties and electronic structures of CuSbS2, CuSbSe2, and CuSb(S1−xSex)2 solid solution
Authors: Wada Takahiro , Maeda Tsuyoshi
Published: April 2022

To clarify electronic structures of CuSbS2, CuSbSe2, and CuSb(S1−xSex)2 solid solutions, these powder samples were synthesized by a mechanochemical process and post‐heating. CuSbS2 and CuSbSe2 have indirect and direct band gaps, of which the direct band gaps are a little wider than the indirect band gaps. The ionization energies of CuSb(S1−xSex)2 (0.0 ≤ x ≤ 1.0) powders were measured by photoemission yield spectroscopy (PYS). Energy levels of the valence band maximum (VBM) of the CuSb(S1−xSex)2 samples were estimated from the ionization energies. The electron affinity, energy level of conduction band minimum (CBM), of the CuSb(S1−xSex)2 samples could also be determined by adding the value of the optical band gap to the energy level of the VBM. The energy level of the VBM of the CuSb(S1−xSex)2 system monotonically increases from −5.45 eV for CuSbS2 (x = 0.0) to −5.15 eV for CuSbSe2 (x = 1.0). On the other hand, the energy levels of the indirect CBM of the CuSb(S1−xSex)2 system slightly decrease from −4.05 eV for CuSbS2 to −4.11 eV for CuSbSe2. The energy levels of the direct CBM also slightly decrease from −4.00 eV for CuSbS2 to −4.07 eV for CuSbSe2. We show the band alignment of CuSbS2 (CuSbSe2)‐based solar cells with a standard device structure of ZnO/CdS/CuSbS2 (CuSbSe2) absorber.
A closer look into metastable effects of Cu(In,Ga)Se2 solar cells
Authors: Lavrenko Tetiana , Walter Thomas , Plesz Balázs
Published: April 2022

In this contribution, metastabilities of Cu(In,Ga)Se2 (CIGS)/CdS thin films are discussed based on photoluminescence (PL) imaging and complementary vibrating Kelvin probe (VKP) measurements. It has been shown that thermal treatment of CIGS/CdS thin films leads to the PL intensity quenching and a change in a surface band‐bending as deduced from VKP measurements under illumination. The impact of white light soaking has the opposite effect as compared to heat treatment: elevated temperatures enhance surface band‐bending whereas illumination leads to at least a partial band‐flattening. Furthermore, it has been found that etching away the CdS buffer layer reduces the previously measured band‐bending significantly pointing out the importance of the buffer layer deposition process. Moreover, the investigation of P1 scribes revealed that surface potentials in the vicinity of the patterning lines differ from the surface potentials measured on cells what is also reflected in the PL images as differences in the intensity between the bulk of the cells and P1 scribes. This observation suggests that the influence of P1 scribing parameters on electrical characteristics of CIGS solar cells has to be studied additionally as they can significantly affect the overall efficiency of the cell.
Photoluminescence study of Cu2ZnSnS4 thin film solar cells
Authors: Yamazaki M. , Nakagawa M. , Jimbo K. , Shimamune Y. , Katagiri H.
Published: April 2022

Cu2ZnSnS4 (CZTS) is considered as a non‐toxic and low‐cost absorber material for solar cells, which has optimum direct bandgap energy for solar energy absorption and high absorption coefficient. In order to achieve higher solar cell efficiencies of CZTS, a better understanding about its defect structure is required. In this study, the defect levels of CZTS are investigated by means of photoluminescence measurements. At temperatures lower than 150 K, a broad emission band around 1.17 eV was observed. The emission band around 1.38 eV was observed at temperatures higher than 125 K. Measurements of PLE spectra for these two emissions have been performed. The emission at 1.17 eV is found to be from the CZTS layer, and its thermal activation energy of 40 ± 9 meV was obtained from the temperature dependence of PL spectra. The emission at 1.38 eV is found to be from the CdS layer.
Quenching interface recombination in wide bandgap Cu(In,Ga)Se2 by potassium treatment
Authors: Zahedi‐Azad Setareh , Scheer Roland
Published: April 2022

In this contribution, we report on the increase of the output voltage for wide bandgap (Eg > 1.4 eV) Cu(In,Ga)Se2 films by doping potassium via post‐deposition treatment of the grown absorber layer. Also the carrier collection is improved by Potassium fluoride treatment (KF). The difference between KF‐treated and untreated samples is investigated using J–V parameters, external quantum efficiency (EQE), and VOC(t) transients under red illumination. Statistics shows an increased activation energy of saturation current and a trend toward a positive dVOC/dt. Thus the increased VOC can be explained through partially quenched recombination at the interface of buffer/absorber layer.
Structural analysis of co‐evaporated In2S3 and In2S3:V for solar cell absorber applications
Authors: Wägele Leonard A. , Rata Diana , Gurieva Galina , Scheer Roland
Published: April 2022

In this study we use co‐evaporation to grow In2S3 thin films on glass substrates and X‐ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive X‐ray spectroscopy (EDX) to analyse the structural properties of annealed In2S3 and V‐doped In2S3 for intermediate band solar cell application. We find co‐evaporated In2S3 to be polycrystalline on float glass and with improved crystallinity after annealing in S‐atmosphere. We confirm that excessive incorporation of vanadium into the host structure is possible without formation of secondary crystalline phases. The analysis indicates a reduced crystalline quality after V doping.
The influence of phonon focusing on density of states and the Knudsen phonon gas flow in nanowires with different types of anisotropy of elastic energy
Authors: Kuleyev I. I. , Bakharev S. M. , Kuleyev I. G. , Ustinov V. V.
Published: April 2022

The influence of elastic energy anisotropy on phonon density of states (PDOS) and phonon mean free paths for acoustic modes in nanowires of cubic crystals with positive (Ge, Si, LiF, GaSb, GaAs, and GaN) and negative (CaF2, SrF2, and PbS) anisotropy of the second order elastic moduli has been investigated. The proposed calculation method allows one to determine angular distributions of the PDOS of fast and slow quasi‐transverse modes in elastically anisotropic crystals for phonon focusing and defocusing regions. It has been shown that the PDOS and the phonon mean free paths in the cubic crystals take maximum and minimum values in the directions of phonon focusing and defocusing, respectively. Moreover, the anisotropy of the crystals differs qualitatively: the maxima values for the type‐I crystals correspond to the minima for the type‐II crystals. The heat flux directions that provide the maximum and minimum phonon thermal conductivity in the nanowires have been identified.
Electron beam induced excess carrier concentration
Authors: Yakimov E. B.
Published: April 2022

The maximum excess carrier concentration in Si under the electron beam irradiation is calculated as a function of beam energy and diffusion length. The values obtained are compared with approximated ones. It is shown that the Berz and Kuiken expression can be used for the excess carrier concentration estimation. A possibility to reach the low excitation conditions in EBIC and CL measurements on Si is demonstrated.
Deep level centers in electron‐irradiated silicon crystals doped with copper at different temperatures
Authors: Yarykin Nikolai , Weber Jörg
Published: April 2022

The effect of bombardment with energetic particles on the deep‐level spectrum of copper‐contaminated silicon wafers is studied by space charge spectroscopy methods. The p‐type FZ‐Si wafers were doped with copper in the temperature range of 645–750 °C and then irradiated with the 1015 cm−2 fluence of 5 MeV electrons at room temperature. Only the mobile Cui species and the CuPL centers are detected in significant concentrations in the non‐irradiated Cu‐doped wafers. The properties of the irradiated samples are found to qualitatively depend on the copper in‐diffusion temperature Tdiff. For Tdiff > 700 °C, the irradiation partially reduces the Cui concentration and introduces additional CuPL centers while no standard radiation defects are detected. If Tdiff was below ∼700 °C, the irradiation totally removes the mobile Cui species. Instead, the standard radiation defects and their complexes with copper appear in the deep‐level spectrum. A model for the defects reaction scheme during the irradiation is derived and discussed.

DLTS spectrum of the Cu‐contaminated and then irradiated silicon qualitatively depends on the copper in‐diffusion temperature.
The beginning of wine and viticulture
Authors: Estreicher Stefan K.
Published: April 2022

The wild ancestor of most of today's grape cultivars is the eastern Vitis vinifera sylvestris. Archaeological, genetic, ampelographic, and linguistic evidence point to Transcaucasia (today's Georgia, Armenia, and Azerbaijan) and Eastern Anatolia as the regions where V.v. sylvestris was domesticated and the first wines made. This occurred in early Neolithic times, over 8000 years ago. But the earliest‐known archeological and chemical proof of wine‐making is just over 7000 years old. It was unearthed at Hajji Firuz Tepe, a Neolithic site in North‐Western Iran. It took thousands of years for wine and viticulture to reach Western Europe and the rest of the world. The key points of the early history of wine and viticulture are the topic of this contribution.
Influence of strain, donor concentration, carrier confinement, and dislocation density on the efficiency of luminescence of Ge‐based structures on Si substrate
Authors: Schwartz Bernhard , Reiche Manfred , Kittler Martin
Published: April 2022

Electroluminescence (EL) of light‐emitting diodes (LED) with different active regions and photoluminescence (PL) of Ge layers embedded in Si barriers on Si substrates has been studied. Increasing the tensile strain in the active region of Ge LEDs by using GeSn virtual substrate technology leads to an enhancement of the direct band luminescence. An intensity increase by a factor of four is achieved due to n‐type doping with an antimony concentration of 3 × 1019 cm−3. The EL of LEDs with a GeSn/Ge multi quantum well structure as active region show an increased direct band luminescence of GeSn by a factor of 16 compared to an intrinsic Ge LED, revealing the advantage of carrier confinement. A high density of threading dislocations, due to the lattice mismatch of Ge and Si, causes a huge drop of PL intensity in the range of one to two orders of magnitude in the temperature range from 80 to 350 K. Thin and pseudomorphically grown Ge layers between Si barrier layers exhibit a huge PL intensity due to the absence of threading dislocations. Taking into account the thickness of the active region the direct band luminescence intensity is increased by two orders of magnitude.
Two‐stage mechanism of Zn nanoparticles formation in ZnO crystal by Nd:YAG laser radiation
Authors: Medvids Arturs , Grase Liga , Onufrijevs Pavels , Mimura Hidenori , Yukhymchuk Volodymyr , Mezinskis Gundars
Published: April 2022

Zn nanoparticles characteristics like size and concentration can be tailored by laser irradiation. A pulsed Nd:YAG laser was operated at a wavelength of 266 nm, pulse duration of 3 ns, and a maximum intensity of 315.0 MW cm−2. Zinc nanoparticles formation is proposed to occur in two stages. In the first stage, Zn interstitials (Zni) are generated at the irradiated site. In the second stage, Zni agglomerate to increase the size of Zn nanoparticles up to 120 nm. Zni formation is implied from an increase in the electrical conductivity, but agglomeration occurs from heat treatment provided by laser irradiation. Single laser pulse irradiation creates small nanoparticles about 7 nm in size. Further laser pulses reduces the concentration of small nanoparticles and increases the size of nanoparticles up to 120 nm. The size and structure was observed by field emission scanning electron microscope and Raman spectroscopy. Topography and electrical conductivity was mapped by atomic force microscopy.
Intergranular barrier height fluctuations in polycrystalline semiconductors
Authors: Buono C. , Schipani F. , Ponce M. A. , Aldao C. M.
Published: April 2022

The punctual character and random nature of the impurity positions in depletion regions lead to inhomogeneities that can significantly affect the potential intergranular barriers at polycrystalline semiconductors and, in general, of potential barriers at any semiconductor interface. This would reflect in Arrhenius plots for the electrical conductivity that become curved due to fluctuations of the intergranular barrier heights. Experimental results for polycrystalline tin oxide can be fitted assuming thermionic emission conduction at grain boundaries with a Gaussian distribution of barrier height fluctuations. However, resorting to a computational numerical model, we found that spatial fluctuations in barrier heights due to the discreteness of the donors and their statistical distribution at the depletion region differ from a Gaussian distribution. The type of obtained fluctuations, considering thermionic emission conduction, cannot explain the Arrhenius plots for the electrical conductivity found experimentally, especially at low temperature. Conversely, the tunneling contribution to conduction, without resorting to fluctuations, presents the observed trends.
Dislocation trails in Si: Geometry and electrical properties
Authors: Orlov V. I. , Yakimov E. B. , Yarykin N.
Published: April 2022

Dislocation trails, the quasi‐2D defects left behind gliding dislocations, are studied in terms of the dislocation motion geometry. The individual dislocation half‐loops are introduced in silicon crystals at 600 °C from the sources on the tensile {100} surface. The electrically active dislocations and dislocation trails are revealed by their recombination activity using the LBIC and EBIC techniques. It is found that only one 60° segment of the dislocation half‐loop creates the dislocation trail, while the screw and differently aligned 60° segments do not. Reversal of the dislocation motion is observed to alternate the role of the 60° segments in the dislocation trail formation. All results are consistent with the model which assumes that the electrically active dislocation trails are created by the dissociated 60° dislocation with the 90° leading partial.

LBIC image of the defects formed by expansion of the dislocation half‐loops created from the tensile {100} silicon surface.
Impact of damages in monocrystalline n‐Si on material photosensitivity
Authors: Tigishvili Marina , Khuchua Nina , Gapishvili Nodar , Sakharova Tatiana , Dolidze Nugzar , Jibuti Zurab , Peradze Giorgi , Melkadze Revaz
Published: April 2022

The optical and electrical characteristics of p–n photodiodes based on monocrystalline n‐Si (wafers with ρ = 70 and 10 Ohm · cm and SOI) implanted with B+ in the dose range of 1 × 1014–1 × 1015 сm−2 and annealed at 900 °C (20 min) are studied. The p–n structures exhibit photosensitivity in the short‐wavelength infrared region (SWIR) with different maximum intensities depending on dose and n‐Si resistivity. Leakage currents are also dose‐dependent. The character of the SOI spectra is somewhat different. The optical and electrical properties of p–n photodiodes are described in terms of formation of extended defects with deep levels in the bandgap appearing after B implantation and annealing of n‐Si. The importance of the damaged surface layer in the starting material for the observed effects is confirmed experimentally. The relation of the SWIR photoresponse intensity to the content of C and O gettered to the p–n structure surface is revealed. The innovative aspects of technology application are discussed.
Characterization of light‐activated Cu defects in silicon: Comparison with the recombination activity of metallic precipitates
Authors: Inglese Alessandro , Vahlman Henri , Kwapil Wolfram , Schön Jonas , Savin Hele
Published: April 2022

The presence of copper contamination is known to severely degrade the minority carrier lifetime of p‐type silicon upon exposure to illumination. In this contribution, we have analyzed the recombination activity of light‐activated copper defects in deliberately Cu‐contaminated p‐type silicon by means of a recombination model that quantitatively defines the effect of metallic precipitates on minority carrier lifetime. The excellent agreement between the model and the experimental data indicates that (i) the formation of Cu precipitates is the probable root‐cause behind Cu‐LID and (ii) in the samples examined in this work, the precipitate radius varies between few to several tens of nm with corresponding densities estimated to be in the range of 108–1010 cm−3. Further evidence of these results was obtained from the analysis of temperature‐dependent lifetime data. While applied here to light‐activated copper defects, the procedure described in this article can be applied for characterizing lifetime‐limiting precipitates originated by other transition metals (e.g., Fe or Ni).
Thermal stability of DRL in n‐GaN
Authors: Medvedev Oleg , Vyvenko Oleg , Bondarenko Anton
Published: April 2022

Impact of stepwise annealing in the temperature ranges 300–750 K in vacuum chamber of scanning electron microscope on the cathodoluminescence of freshly introduced a‐screw dislocations in low‐ohmic GaN was investigated. Dislocation related luminescence (DRL) exhibits wide intense band at energy of about 3.12 eV at the room temperature and exceed an intensity of the near band edge emission. DRL intensity decreases with the temperature increase but remains detectable up to 450 K. Annealing at the temperatures up to 500 K does not change significantly structure of dislocations introduced at room temperature, while after the treatments at higher temperatures of up to 750 K the dislocations expand their length remaining in basal plane. The treatments however do not change DRL optical properties of the individual dislocations after cool down to room temperature.
Construction of the Energy Band Diagram of Hydrogen Terminated Diamond and Silicon Nanowires
Authors: Challinger Susanna , Baikie Iain , Birdwell A. Glen , Strehle Steffen
Published: April 2022

We demonstrate the use of a combined ambient pressure and UHV photoemission system for absolute work function characterization. We describe measurements of the valence band position of Hydrogen Terminated Synthetic Diamond (HTSD) under different pressures. The diamond exhibits a nanoscale surface conductivity with a 2D hole gas of ≈10 nm depth. The same system also allows contact potential difference Kelvin probe measurements for determination of relative Fermi level position from 1 to 1.1 × 10−11 Bar. Combined with UV‐Surface Photovoltage determination of the band gap, this allows a complete reconstruction of the surface energy band diagram of this material. The valence band edge was found to be 4.9 eV under ambient conditions and 4.4 eV under UHV, relative to the vacuum level. The ambient pressure photoemission technique was also used to reconstruct the energy band diagram of bottom‐up grown silicon nanowires. They had a valence band maximum at 5.04 ± 0.05 eV. Both the HTSD and silicon nanowires had high photoemission yield characteristics which suggests that these materials could be used as an electron source. This illustrates the suitability of photoemission and Kelvin probe techniques for investigating the macroscopic work function characteristics of surfaces with nanostructures and nanoscale surface conductivity.
Nanoscale Mapping of Semi‐Crystalline Polypropylene
Authors: Abrams Kerry J. , Wan Quan , Stehling Nicola A. , Jiao C. , Talari Abdullah C. S , Rehman Ihtesham , Rodenburg Cornelia
Published: April 2022

We reveal nanoscale information of semi‐crystalline polypropylene with the use of a new secondary electron hyperspectral imaging technique. The innovative combination of cryo‐SEM and low voltage allows for the optimized imaging of these beam‐sensitive materials. Through the collection of secondary electron hyperspectral imaging data, mapping of molecular order on the nano‐scale in the scanning electron microscope (SEM) can be achieved.
Optical Modeling of Ultrathin Silicon Solar Cells with PC1D
Authors: Abenante Luigi
Published: April 2022

We show that the optical diffusion model embedded in the numerical simulation program PC1D systematically underestimates light‐generated currents in thin textured Si solar cells. The demonstration exploits the exact analytical solution to minority‐carrier transport in uniformly doped regions and the fact that, at the first pass of internal light, the average optical propagation angle, θ, with respect to the device normal is determined by surface texture. We provide a simple correction procedure to remove the aforementioned systematical error. One can so reliably model with PC1D the optical performance of textured thin devices at standard Lambertian regimen (θ = 60° at all wavelengths, λ) that starts at either the first or the second pass of trapped light. We exploit such a possibility to scrutinize with PC1D a reported non‐standard Lambertian optical model, where θ varies with λ.
Strain and Compositional Analysis of (Si)Ge Fin Structures Using High Resolution X‐Ray Diffraction
Authors: Schulze Andreas , Loo Roger , Witters Liesbeth , Mertens Hans , Gawlik Andrzej , Horiguchi Naoto , Collaert Nadine , Wormington Matthew , Ryan Paul , Vandervorst Wilfried , Caymax Matty
Published: April 2022

The performance of heterogeneous 3D transistor structures critically depends on the composition and strain state of the buffer, channel, and source/drain regions. In this paper we discuss the value of in‐line high resolution X‐ray diffraction (HRXRD) measurements based on three representative examples. First, we analyzed the strain state of etched Ge fins in the two in‐plane directions. We could verify a loss in channel strain after growth of a Si cap which we attribute to Ge reflow. Secondly, we studied the composition and strain state of relaxed SiGe fins selectively grown in an STI matrix where we found an anisotropic in‐plane strain state with significantly reduced relaxation in the direction along the fin. Finally, we used HRXRD for the analysis of complex multilayer fin structures which are relevant for horizontal nanowire FETs that are candidates to replace FinFETs below the 7 nm technology node. With this example we could demonstrate that HRXRD is capable of providing insight into fin stress created by interlayer dielectrics (ILD0).
Scan‐Free Grazing Emission XRF Measurements in the Laboratory Using a CCD
Authors: Szwedowski Veronika , Baumann Jonas , Mantouvalou Ioanna , Bauer Leona , Malzer Wolfgang , Kanngießer Birgit
Published: April 2022

The rapid development of new classes of nanomaterials calls for easy access methods in order to quantify properties essential for their functionality, e.g., interdiffusion of elements at interfaces, or elemental dopant, or depth profiles. Non‐destructive methods, like X‐ray fluorescence (XRF), are of special interest, for preserving materials and offering the possibility to incorporate the analysis in a production process. In‐depth XRF methods for the characterization of nanomaterials are up until now limited to synchrotron radiation facilities. A novel scan‐free grazing emission XRF (GEXRF) setup is presented utilizing conventional and low‐cost hardware, acting as a transfer of a synchrotron method into the laboratory. A chromium target X‐ray tube with a polycapillary lens is used as X‐ray source and a conventional CCD as the 2D energy‐dispersive detector. To confirm the feasibility of the described setup a nanometer‐layered titanium‐aluminium sample is measured. An energy‐dispersive spectrum is obtained in single‐photon‐counting‐mode from the CCD measurements and first GEXRF profiles generated. A semi‐quantitative evaluation of this setup is implemented by comparing the measured results with simulations, allowing conclusions about the investigated samples’ elemental, compositional, and structural layer‐by‐layer characteristics.
Characterization of Nanometer‐Sized Oxygen Precipitates in Highly B‐Doped Czochralski Silicon
Authors: Kot Dawid , Kissinger Gudrun , Schubert Markus Andreas , Marschmeyer Steffen , Schwalb Georg , Sattler Andreas
Published: April 2022

We use a wide variety of analytical methods to characterize nanometer‐sized oxygen precipitates in highly B‐doped Czochralski (CZ) silicon. Due to the enhanced precipitation of oxygen in this type of wafer, the precipitate density reaches a value of 1 × 1013 cm−3 already after short annealing. On the one hand, this provides an excellent possibility for testing the detection limits of different methods and on the other hand the knowledge on oxygen precipitation in p+ material can be broadened. In order to study density, size, and morphology of oxygen precipitates, we exploit scanning transmission microscopy (STEM), reactive ion etching (RIE), and preferential etching. STEM is also used to determine size distribution and energy dispersive X‐ray spectroscopy (EDX) and electron energy loss spectroscopy (EELS) are used to investigate the composition of oxygen precipitates. In annealed samples, oxygen precipitates, dislocation loops, and stacking faults are found. The dislocation loops disappear after long annealing in contrast to the stacking faults which are detected in all samples annealed at 1000 °C. It is found that the long anneal at 1000 °C leads to the formation of two size fractions of precipitates. This process is similar to Ostwald ripening. The precipitates are octahedral, consist of SiO2 and the B concentration is below the detection limit of the methods used here. The obtained results are in good agreement with the nucleation model of highly doped wafers proposed by Sueoka.
Effect of Cooling Rate on Dopant Spatial Localization and Phase Transformation in Cu‐Doped Y‐Stabilized ZrO2 Nanopowders
Authors: Korsunska Nadiia , Baran Mykola , Vorona Igor , Nosenko Valentyna , Lavoryk Serhiy , Polishchuk Yuliya , Kladko Vasyl , Portier Xavier , Khomenkova Larysa
Published: April 2022

The effect of calcination temperature (TC = 500–1000 °C) and cooling rate on the dopant distribution in Cu‐doped Y‐stabilized ZrO2 nanopowders is studied. The powders are produced by co‐precipitation technique and investigated by attenuated total reflection, UV‐vis diffuse reflectance, electron paramagnetic resonance, and transmission electron microscopy methods. The cooling rate is found to affect the amount of Cu substances on grain surface, the powders subjected to fast cooling (quenching) showed higher amount of Cu‐related complexes on the grains’ surface than their counterparts cooled with furnace after calcination. It is observed that Cu impurities diffuse inside ZrO2 grains from Cu‐related surface substances when TC < 800 °C. This process is accompanied by the enhancement of 275‐nm absorption band caused by oxygen vacancies formation. For TC > 800 °C, outward migration of Cu dopants takes place. Simultaneously, the intensity of 275‐nm absorption band decreases, the monoclinic ZrO2 phase forms and its contribution rises with TC. It is proposed that monoclinic phase formation is caused by the replacement of Cu atoms from lattice sites to interstitials leading to an appearance of the channels for Y out‐diffusion via cation vacancies and destabilization of ZrO2 tetragonal phase.
Photoluminescence from Ordered Ge/Si Quantum Dot Groups Grown on the Strain‐Patterned Substrates
Authors: Dvurechenskii Anatoly , Zinovieva Aigul , Zinovyev Vladimir , Nenashev Alexey , Smagina Zhanna , Teys Sergey , Shklyaev Aleksandr , Erenburg Simon , Trubina Svetlana , Borodavchenko Olga , Zhivulko Vadim , Mudryi Aleksandr
Published: April 2022

The photoluminescence (PL) properties of combined Ge/Si structures representing a combination of large (200–250 nm) SiGe disk‐like quantum dots (QDs) and the groups of smaller (40–50 nm) laterally ordered QDs grown on the nanodisk surface are studied. The experimental results are analyzed basing on the calculations of energy spectra, electron and hole wave functions. It is found that the strain accumulation in multi‐layered structure is the main factor providing the room temperature PL. The new type of QD structures that should provide the observation of enhanced PL from SiGe QDs at room temperature is proposed. The structures represent the stacked compact groups of laterally aligned QDs incorporated in Si at the distance 30–40 nm above the large nanodisks.
Tuning the Work Function of Si(100) Surface by Halogen Absorption: A DFT Study
Authors: Bertocchi Matteo , Amato Michele , Marri Ivan , Ossicini Stefano
Published: April 2022

First‐principles calculations of work function tuning induced by different chemical terminations on Si(100) surface are presented and discussed. We find that the presence of halogen atoms (I, Br, Cl, and F) leads to an increase of the work function if compared to the fully hydrogenated surface. This is a quite general effect and is directly linked to the chemisorbed atoms electronegativity as well as to the charge redistribution at the interface. All these results are examined with respect to previous theoretical works and experimental data obtained for the (100) as well as other Si surface orientations. Based on this analysis, we argue that the changes in the electronic properties caused by variations of the interfacial chemistry strongly depend on the chemisorbed species and much less on the surface crystal orientation.
Hydrophilic Luminescent Silicon Nanoparticles in Steric Colloidal Solutions: Their Size, Agglomeration, and Toxicity
Authors: Herynková Kateřina , Šimáková Petra , Cibulka Ondřej , Fučíková Anna , Hubálek Kalbáčová Marie
Published: April 2022

Luminescent silicon nanoparticles are promising for intracellular biological research as luminescent probe for in vitro and in vivo studies. We prepared nanoclusters of hydrophilic highly porous silicon having the size around 100 nm, composed of nanocrystals ∼2.5 nm in size, by electrochemical etching. Colloidal suspensions of the nanoparticles in steric organics (bovine serum albumin (BSA), glutamic acid, dextran, and glycine) were prepared to attempt to stabilize the nanoparticles and prevent their further agglomeration. The zeta potential differs from sample to sample – BSA and glycine solutions have zeta potential between −30 and −40 mV indicating good stability of nanoparticles in the solutions, while the zeta potentials of water (−24 mV), dextran (−10 mV), and glutamic acid (−14 mV) are showing that nanoparticles tend to agglomerate. Strong orange luminescence of nanoparticles is situated between 600 and 700 nm and remains stable in all used organic colloidal solutions. Performed study of in vitro toxicity revealed that sterically stabilized silicon nanoparticles are cytotoxic only at the highest used concentration (500 μg ml−1) of the silicon nanoparticles in water and BSA. Only in the case of glycine a significant decrease of the cell viability was observed already at a lower concentration of 250 μg ml−1 and is caused probably by glycine itself.
Carrier Multiplication in Silicon Nanocrystals: Theoretical Methodologies and Role of the Passivation
Authors: Marri Ivan , Govoni Marco , Ossicini Stefano
Published: April 2022

Carrier multiplication is a non‐radiative recombination mechanism that leads to the generation of two or more electron–hole pairs after absorption of a single photon. By reducing the occurrence of dissipative effects, this process can be exploited to increase solar cell performance. In this work, we introduce two different theoretical fully ab initio tools that can be adopted to study carrier multiplication in nanocrystals. The tools are described in detail and compared. Subsequently, we calculate carrier multiplication lifetimes in H‐ and OH‐terminated silicon nanocrystals, pointed out the role played by the passivation on the carrier multiplication processes.
An innovative ion sensitive device based on side‐contacted field effect diode
Authors: Mohammadi Ehsan , Manavizadeh Negin
Published: April 2022

In this paper, side‐contacted field effect diode as an ion sensitive device is proposed to take advantages of field effect diodes family in sensing ionic species in solutions. To analyze the behavior of ion sensitive side‐contacted field effect diode, an accurate model has been developed in a simulation environment tool to mimic the characteristics of the solution and the results compared with the literature. While dual gate ion sensitive FETs have been introduced to beat the Nernst limit, results show that dual gate ion sensitive side‐contacted field effect diodes can provide better performance. Effects of various parameters such as silicon body thickness and doping concentration have been studied. In contrast of ISFETs, the proposed device offers more sensitivity at the thicker silicon body. Results indicate that dual gate ion sensitive side‐contacted field effect diodes can be regarded as an interesting candidate for bio‐sensing applications.
Ellipsometric and X‐Ray Spectrometric Investigation of Fibrinogen Protein Layers
Authors: Kalas Benjamin , Pollakowski Beatrix , Nutsch Andreas , Streeck Cornelia , Nador Judit , Fried Miklós , Beckhoff Burkhard , Petrik Péter
Published: April 2022

Bovine fibrinogen monolayers on thin gold films and glassy carbon substrate were investigated using grazing incidence X‐ray fluorescence (GIXRF) and spectroscopic ellipsometry (SE). The aim was to determine the amount of protein and to develop models and references for the SE measurement. Both methods were capable of measuring protein amount in the range of μg cm−2 with a sensitivity below 10%, which suggests the use of both techniques as complementary, combined methods. To do it with a high confidence, the lateral uniformity and the stability of the layers during transportation has to be investigated in more detail in the future.
Transport Properties of Graphene‐BiTeI Hybrid Structures
Authors: Tajkov Z. , Visontai D. , Rakyta P. , Oroszlány L. , Koltai J.
Published: April 2022

Recent studies have shown that heterostructures comprised of graphene and certain chalcogenides are robust two‐dimensional (2D) topological insulators. We developed a simplified model Hamiltonian for such systems and investigated their properties as the function of various parameter values. We mapped the phases of the system that can behave as an insulator, metal or topological insulator. We used this simplistic model to calculate transport characteristics on experimentally relevant sample sizes.
Determination of Shape and Sphericity of Silicon Quantum Dots Imaged by EFTEM‐Tomography
Authors: Hiller Daniel , Gutsch Sebastian , López‐Vidrier Julian , Zacharias Margit , Estradé Sònia , Peiró Francesca , Cruz‐Matías Irving , Ayala Dolors
Published: April 2022

The shape of size‐controlled silicon nanocrystals (Si NCs) embedded in SiO2 is investigated by tomographic energy‐filtered transmission electron microscopy (EFTEM). The sphericity of the quantum dots is determined by computational analyses. In contrast to other fabrication methods, we demonstrate that the NCs in superlattices are non‐agglomerated, individual clusters with slightly oblate spheroidal shape. This allows for low surface‐to‐volume ratios and thereby low non‐radiative defect densities as required by optoelectronic or sensing applications. A near‐spherical shape is also a prerequisite for the direct comparison of Si quantum dots (QDs) with theoretical simulations.
Use of Rayleigh‐Rice Theory for Analysis of Ellipsometry Data on Rough CIGS Films
Authors: Jensen Søren A. , Rosu Dana Maria , Hertwig Andreas , Hansen Poul‐Erik
Published: April 2022

Ellipsometry is a useful tool for studying the optical properties of thin films such as photovoltaic devices. We employ Müller matrix ellipsometry to study the thin film photovoltaic material copper indium gallium selenide Cu(In,Ga)Se2 (CIGS), a commercially relevant material with high energy conversion efficiency. Confocal microscopy reveals an rms roughness of 68 nm, which greatly affects the ellipsometry data. Rayleigh‐Rice theory is employed to account for the optical properties of the surface roughness in the ellipsometry experiment, and a library search method is used to compare Müller parameters calculated for various CIGS compositions, to the measured data. The Müller parameters calculated with the Rayleigh‐Rice model are found to correspond well with the measured data, and a surface roughness of 37 nm and a correlation length of 125 nm are extracted.
Ab Initio Study of Ferromagnetism in Mn‐doped AlGaP2
Authors: Kang Byung‐Sub , Song Kie‐Moon , Lee Haeng‐Kie
Published: April 2022

We investigated the electronic and magnetic properties for a diluted magnetic semiconductor of 3d‐metal Mn‐doped AlGaP2 chalcopyrite alloys by using the first‐principle calculations. The chalcopyrite AlGaP2 has the semiconductor characters. The ferromagnetism with high magnetic moment of Mn is originated from the 3d(Mn)‐ and 3p(P)‐bands exchange couplings. When the singlet Ga or Al vacancy, or the mixed vacancies including P vacancy exists in the chalcopyrite AlGaP2:Mn, the high magnetic moment of Mn exhibits because the exchange interactions between the localized carrier trapped by vacancy and neighboring Mn2+ ions aligned by the Mn2+ spins around the carrier localization center. The AlGaP2:Mn without the defects exhibits the ferromagnetic and half‐metallic state. However, the ferromagnetic half‐metallicity disappears in the singlet vacancy and the mixed vacancies, such as Al+Ga, Al+P, or Ga+P. These electronic and magnetic properties were compared with that of AlGaP2:Mn thin film.
Retraction: Stress Relaxation Mechanism in the Si‐SiO2 System and Its Influence on the Interface Properties
Authors: Kropman Daniel , Seeman Viktor , Dolgov Sergei , Heinmaa Ivo , Medvid Artur
Published: April 2022

The above article,1 published online on 22 July 2016 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by decision of the journal Editor‐in‐Chief, Stefan Hildebrandt, and Wiley‐VCH GmbH & Co. KGaA. The retraction has been made since essential contents of the article have already been published by the corresponding author in Phys. Status Solidi A 2003, 198, 297; Physica B 2009, 404, 5153; IOP Conf. Ser.: Mater. Sci. Eng. 2011, 25, 012018; Solid State Phenom. 2011, 178–179, 259.

The corresponding author apologizes on behalf of his colleagues for the situation.

[1] D. Kropman, V. Seeman, S. Dolgov, I. Heinmaa, A. Medvid, Phys. Status Solidi C 2016, 13, 790.
Post‐ictal diffuse alveolar haemorrhage: clinical profile based on case reports
Authors: You Jee Young , Stoller James
Published: April 2022

Diffuse alveolar haemorrhage (DAH) after a generalized tonic–clonic seizure is a rarely described illness likely involving physical disruption of alveolar–capillary interface similar to the mechanism of neurogenic pulmonary oedema. Based on our review of the English literature, only 11 cases have been reported to date. Recognition of this sparsely reported entity is important for optimal management, including avoidance of medications that have been implicated in causing DAH. Current experience with two additional patients with post‐ictal DAH extends the reported experience to 13 and summarizes what is, to our knowledge, the entire experience of such patients reported in the English literature. This case report highlights the key aspects of clinical presentation, radiological and pathological findings, clinical course and management implications with the goal of enhancing awareness of this condition by respiratory clinicians.