Silicon nanocrystals (Si-Ncs)-based devices are some of the most studied nanomaterials and could be of great interest in many fields such as electronics1, optical sensing2, photovoltaics3 and biomedicine4. First of all, it is important to control their size, shape and aggregation which are parameters related to their potential applications. In our case, these Si-Ncs are embedded in an insulating dielectric matrix of SiOxNy, resulting in a composite material with a tunable effective bandgap. Doping Si-Ncs can enlarge their applicability by modifying their electrical properties5, the effective bandgap5, the light absorption range and the nanoparticles photoluminescence. In this study, we used a magnetron sputtering deposition system to deposit silicon rich silicon oxynitride (SiOxNy) thin films. Then, n- and p-type dopants such as boron, arsenic and phosphorus were introduced in the thin films using ion implantation which was carried out at different doses and accelerating energies5. Thanks to a thermal treatment at high temperature, silicon atoms diffuse and nucleate to form silicon nanostructures with size varying between 1.5 nm and several dozen nanometers. This step is necessary for the phase separation leading to the nanoparticles nucleation. Atom probe tomography (APT) and energy dispersive X-ray mapping in scanning TEM mode, coupled with spectrum imaging on silicon plasmon, were performed to localize the dopant impurities versus the Si-Ncs. The results have showed that n-type (P and As) dopants were energetically favored to be placed into the Si-Ncs core, whereas p-type dopants are preferentially located at the Si-NCs/SiOxNy interface. The effect of composition and post-deposition annealing temperature on the Si-Ncs light-emitting properties was investigated by the examination of photoluminescence (PL) evolution. The dopants distribution profiles within the host matrix were determined by Rutherford Backscattering Spectroscopy (RBS). EFTEM combined with X Rays mapping analysis have exhibited that the incorporation of arsenic at a high doping level (dose of 5x 1016 As/cm2) leads to an increase of the Si-Ncs size by a factor around 4, precisely from 4 nm to more than 20 nm (Figure 1). On the other hand, the EFTEM-X Rays analysis was unable to detect boron dopants in the SiOxNy films. At this doping level, it could be possible to observe a localized surface plasmon resonance (LSPR) 7. For both n- and p-type dopants, the silicon nanoparticles crystalline fraction was found to be much higher than the undoped structures. The dopants facilitate the nucleation and growth of crystalline nanoparticles. This behavior is quite similar to that observed for thin amorphous silicon films. The results have showed that the nanostructures shape have different behaviors depending on the dopants. Finally Schottky diodes were prepared. The I-V characteristic curves show that the electrical conduction in the -doped structures increases with the dopant doses and we obtained a rectifier behavior. The results have showed that the heavily As-doped silicon structures are limited by the tunnel oxide thickness between the large Si-Ncs. These results are very encouraging when aiming at implementing such nanocomposite materials in photovoltaic solar cells. References: 1. Rev. 2010, 110, 339-458. 2. Photoenergy 2012, 872576. 3. Photovolt.: Res. Appl. 2001, 9, 12-135. 4. J. Nanomed. 2006, 1, 451. 5. Phys. Lett. 2013, 102, No.013116 6. Appl. Phys. 2013, 114 Issue 3 7. Rev. Lett. 2013, 11, 177402. Figure 1

Structural characteristics and luminescence properties of B‐doped silicon nanocrystals (Si‐ncs) embedded in a SiO2 matrix elaborated by ion beam synthesis are investigated. The use of atom probe tomography gives a unique opportunity to experimentally evidence the exact location and composition of B atoms in doped Si‐ncs. These experiments allow to conclude about a favored B location at the periphery of the Si‐ncs depending on their size. In this way, two categories of Si‐ncs can be described: 1) largest Si‐ncs that are B‐doped and where B atoms are located at the Si‐ncs/SiO2 interface, and 2) smallest Si‐ncs that remain undoped but seem to be surrounded by a B‐rich SiO2 shell. These structural characteristics (composition and diameters) are correlated to the photoluminescence properties of these Si‐ncs. These measurements show the well‐known quenching of Si‐ncs luminescence due to high B doping, which allows us to conclude about the environment changes brought by the presence of B in Si‐ncs or of B‐rich shell around Si‐ncs.

Semiconductor nanoparticles are of great interest in the area of microelectronics and can also be used in many optoelectrical devices as for example optical converters for photovoltaic applications. Silicon (Si) and silicon-germanium (SiGe) quantum dots can be used as high-energy photon converters, known as "red-shift" photoluminescence (PL) in solar cells in order to improve their efficiency. We report on the possibility to produce SiGe nanoparticles by Pulsed Laser Deposition (PLD) on silicon dioxide substrates. We keep the focus on the control of morphological properties of nanoparticles considering various deposition parameters like temperature, fluence and the amount of deposited material. Si-0.5 Ge-0.5 controlled ratio is obtained by optimizing the amount of matter ablated successively from Si and Ge pure targets. Rutherford Backscattering Spectroscopy (RBS) is used to confirm the stoichiometry of the deposited structures. Morphological characterization is performed by Atomic Force Microscopy (AFM), determining average diameter, height and density of the nanoparticles. In order to confirm the crystalline character of the deposited particles, Raman analyses have been performed, helping in determining the optimal deposition temperature. PLD allows to condense a very small and controlled amount of material during the deposition process, permitting this way the growth of nanostructures in a 10 nm range. With these dimensions, SiGe quantum dots are subject to have a photoluminescent (PL) behaviour. However, no photoluminescence is observed on the deposited nanoparticles.

Materials consisting of silicon nanocrystals (Si-Ncs) embedded in silicon dioxide (SiO 2 ) are the subject of an intense research activity due to their potential applications for optoelectronic and photonic devices.Moreover, providing charged carriers by introducing n-or p-type dopants in these materials can drastically modify their electrical or optical properties.A plenty of studies focused on the capabilities to change the indirect bandgap of Si-Ncs to direct one and to improve the luminescence efficiency of Si-Ncs by single or co-doping.Recently a particular interest was focused on the localized surface plasmon resonance exhibited by highly doped Si-Ncs [1].In both cases, a perfect control of the doping level and size of Si-Ncs should allow to tune the material properties.However, efficiency of these doped materials is correlated to the dopant location, which should be located in a substitutional site of the Si-Ncs.Then, it requires an accurate control of this parameter to improve and control the properties of these systems.Numerous studies concern the characterization of P doping in Si-Ncs, here, we propose to compare undoped and p-doped (with P or As) Si-Ncs by the use of Atom Probe Tomography (APT) to perform a deep structural analysis at the atomic scale.Further investigations will be done on n-type (B) doping.Three silicon rich silicon oxide films, undoped and As or P doped, were elaborated by using ion beam synthesis process.Implantation was divided into two parts.First one consists in a 29 Si implantation in a 28 SiO 2 200 nm thick layer.Second one consists, for two samples, in another implantation of 75 As or 31 P chose to match with the 29 Si implantation range.Finally, samples were annealed at 1100°C during 4h in pure N 2 to form Si-Ncs. Structural characterization of these thin films was performed combining Timeof-Flight Secondary Ion Mass Spectrometry (Tof-SIMS) and Atom Probe Tomography.Measurements performed in Tof-SIMS allowed us to ensure the reliability of 3-D reconstruction of the tip samples.In undoped as in As or P doped samples, Tof-SIMS revealed a region of interest, corresponding to the implantation range of 29 Si in the 28 SiO 2 thin films, of almost 110 nm of thickness and centered at barely 55 nm from the film surface.Moreover, for As or P doping, it confirms that the implantation of 29 Si and both dopants species match well in the same region.We must note that considering APT composition profiles, the composition reached at the peak center of the implantation by 29 Si (~11 at.%) and As or P (~1.2 at.%) in each sample is almost the same.In each case, 3-D chemical maps obtained after the APT reconstruction show that the annealing treatment performed at 1100°C leads to the clustering of 29 Si and 28 Si without any distinction.The mapping of As and P atoms allowed us to highlight the aggregation of the impurities at the same position than the clustering of Si atoms.Thereby, from a first global view, both doping cases seems to be equivalent.The use of APT allowed us to perform deeper investigation on the Si-Ncs characteristics and on the dopant location.In all samples, the diameter of Si-Ncs has been measured in order to compare the size distributions of Si-Ncs.In undoped as in As doped samples, mean diameter and shape of size distribution are almost the same, but we observed strong difference of these parameters in P doped sample (figure 1.a, 1.b).In fact, for undoped and As doped samples, size 2540

Due to its low diffusivity and high activation rate, arsenic has become the dopant of choice in p/n HgCdTe high operating temperature technology. Its diffusion mechanism, however, remains imprecise. In this work, arsenic diffusion was studied in molecular beam epitaxy HgCdTe structures consisting of alternatively As-doped and intrinsic layers grown on a CdZnTe substrate. The diffusion coefficient of As was extracted from secondary ion mass spectroscopy concentration profiles. Annealings were performed for different temperatures, mercury partial pressures (P Hg), annealing times and cadmium atomic fractions. Fermi-level effect on diffusion was observed, indicating extrinsic conditions for diffusion at high As concentration. Based on the variation of As diffusivity with P Hg and As concentration, we propose that As diffusion occurs on both II and VI sublattices. Our results are consistent with the fact that AsVI diffusion is assisted by the Te interstitial, introducing donor levels in the bandgap, while AsII diffusion is assisted by the cation vacancy.

Nowadays short wavelength infrared (SWIR) imaging based on InP/InGaAs photo-diodes is quite popular for uncooled camera. The state of the art technology is a double layer planar heterointerface focal plane array [1]. But, it remains expensive and only used for defense and scientific applications. Its cost comes essentially from the individually hybridization of photo-diodes array with read-out circuit, by the mean of an indium-bumps flip-chip process. We suggest an alternative method for hybridization, in order to lowering the cost and providing a sustainable process to decrease the pixel pitch, and also increase the possible format. It consists in a direct integration of InP/InGaAs/InP structure above a finished read-out circuit (with CMOS technology) and circular diode architecture.

We report an uncommon study of the insertion of distributions of both volume fraction and depolarization factors in the modeling of the plasmonic properties of implanted Ag nanoparticles (Ag-NPs) in a SiO2 layer when using spectroscopic ellipsometry (SE) characterization. The Ag-NPs were embedded in the SiO2 matrix by Ag+ ion implantation at various doses of 0.5 × 1016, 1 × 1016, 2 × 1016, and 5 × 1016 ions cm−2. The formation of the Ag-NPs in a host matrix of SiO2 was controlled by transmission electron microscopy (TEM). The Ag-NPs are self-organized in the layer, and their mean radius ranges between 2 and 20 nm. The optical properties of layers were extracted by modeling the SE parameters by taking into account the depth profile concentration of Ag-NPs. The mixture of SiO2 and Ag-NP inclusions was modeled as an effective medium according to the shape distributed effective medium theory (SDEMT). In addition to the optical responses, it is shown that this model enables the explanation of the impact of NP shape distribution on the plasmon band and provides precious information about the NP shape characteristics. A good agreement was obtained between ellipsometry and TEM results. The distribution of the volume fraction in the film was found to lead to a gradient of effective dielectric function which was determined by the SDEMT model. The effective dielectric function reveals distinct Ag plasmon resonance varying as the Ag+ ions dose is varied. The real part of the dielectric function shows a significant variation around the plasmon resonance in accordance with the Kramers-Kronig equations. All determined optical parameters by SDEMT are provided and discussed. We highlight that SE combined with SDEMT calculations can be considered as a reliable tool for the determination of the NP shape and volume fraction distributions without the need of TEM.

In order to develop III-V based devices integrated directly above post-processed silicon wafers, low temperature diffusion of zinc in n-type InP and InGaAs is studied at compatible temperatures, below 425 degrees C. We particularly focus on the resulting surface degradation. Efficient Zn diffusion is obtained for InGaAs samples, where the surface remains mirror-like after thermal treatment. Conversely, no significant diffusion occurs in InP where the surface is deeply deteriorated. The stability study for InP under thermal annealing in various ambients allows us to rule out thermal dephosphorization as the main cause of the surface degradation. On the basis of experimental observations and thermodynamic considerations, it is suggested that InP degradation is linked to the direct interaction of Zn and P, inducing the formation of parasitic ZnxP2 alloys, which also hinders the efficient diffusion of Zn into the InP substrate.

Our goal is to use the versatility of ion beam synthesis to grow nanocrystals of InxGa1-xAs alloys embedded in a silicon substrate. We study, first, the annealing conditions necessary to grow well defined InAs and GaAs binary nanocrystals. High dose of As, Ga and In is implanted, respectively, at 130, 130 and 180 keV to have overlapping as-implanted profiles. The nanocrystals growth is then achieved by rapid thermal annealing at various temperatures between 650 and 800 degrees C for 1 min under an argon gas flow. Rutherford backscattering spectroscopy profiles show that no significant impurity out-diffusion occurs below 800 degrees C for both systems. In and As thermal redistributions lead to superposed profiles. Raman spectroscopy measurements prove that InAs nanocrystals are formed above 650 degrees C, while 800 degrees C annealing is necessary to obtain GaAs nanocrystals and show that these thermal budgets are enough to fully recrystallize the implanted layer. Grazing incidence X-ray diffraction patterns exhibit clearly InAs and GaAs related peaks. These results prove that GaAs and InAs nanocrystals can be grown in a common temperature range (700-800 degrees C), opening the route to the growth of ternary InxGa1-xAs alloys in the same conditions. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Co-implantation, with overlapping implantation projected ranges, of Si and doping species (P, As, B) followed by a thermal annealing step is a viable route to form doped Si nanocrystals (NCs) embedded in SiO2. This presentation deals with optical characterizations of both doped and undoped Si-NC prepared by this method. The NC effective presence in the oxide layer and their crystallinity is verified by Raman spectrometry. Photoluminescence (PL) and PL excitation measurements reveal quantum confinement effects and a gradual PL quenching with increasing dopant concentrations. The measured Stokes shift remains constant and its value ∼ 0.2 eV is almost twice the Si–O vibration energy. This suggests that a possible radiative recombination path is a fundamental transition assisted by a local phonon. Lifetime investigations show that PL time-decays follow a stretched exponential. Atomic probe tomography analyses demonstrate that n-type dopants (P, As) are efficiently introduced in the NC core, whereas p-type dopant (B) are located at the NC/SiO2 interface. All together these experimental observations question on possible different carrier recombination paths in P or As doped NC compared to B one's. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

of several new materials in clean rooms, the monitoring of trace metallic contamination is a real and present need. It is well known [1][2][3] that these impurities are detrimental to the efficiency of the microelectronics devices: they could cause crystal defects, act as electron traps, degrade minority carrier lifetime or increase the leakage current. Concerning the noble metallic contaminants (Au, Pt, Ir, Ru, Ag and Pd), now used in microelectronics to improve devices performances, their surface contamination control at low level (< 1010 at.cm-2) remains a great challenge.

In order to overcome the performances, dimensions and cost limit beyond the 22 nm technology node, three-dimensional (3-D) integration with through-silicon-vias (TSVs) has emerged as an effective solution. Another potential of the TSVs is their promises in enabling advanced multi-level chips, integrating heterogeneous CMOS technologies with emerging technologies such as MEMS and bio-chips. As many integration schemes include the need of high aspect ratio TSVs in order to increase silicon thickness for Die bow and warp limitations or decrease TSV diameter for density increase, TSV Metallization, particularly barrier and seed layer deposition, has become a critical process step of the integration. In a previous work, the investigation of a low temperature (200°C) MOCVD TiN film as a barrier layer to prevent copper diffusion was studied. From these studies, it comes out that even a 5nm thin TiN film withstand barrier efficiency thermal test on fullsheet deposition. This barrier shows up a different behavior while being integrated in the high aspect ratio TSV due to subsequent plasma treatment during the deposition. Actually, the plasma densification does not have the same efficiency through the sidewall of the 80 µm deep TSV thereby enabling a different material structure all along the profile of the via. Characterizations of the behavior of the barrier in the TSV then become a great challenge in order to handle the integration protocol both in horizontal and vertical scales. Working at this scale of topology makes standard diffusion methods limited to evaluate the intrinsic diffusion properties into the via. A localized diffusion methods using Tof-SIMS along the sidewall of the TSV was used to overcome these geometrical issues (figure 1). This technique allowed us to compare different type of barriers and the determination of the minimal thickness for the efficiency of these films as a barrier in the TSV. 3-D stacking using TSV involves mechanical and thermal stresses in the Cu TSV itself as well as in the surrounding silicon substrate. As the Cu volume of the TSV becomes important compared to the size of the active components, stresses are induced extrinsically by the interaction of every metallurgical step of the TSV elaboration, including dielectric isolation, barrier/seed layer and copper filling depositions as well as subsequent copper anneals. Stresses can be induced intrinsically by thermal treatment due to the mismatch of thermal expansion between the via material and Si. Usually the X-rays diffraction (XRD) and the stress distribution from the variation of the curvature during the processing is used to measure the stress induced in thin films. Due to the depth of the structure, these methods are limited to measure the stress generated by the TSV. Micro Raman spectroscopy measurements allow measuring the stress induced by every single metallurgical step of the TSV elaboration. For the barrier layer step, the intrinsic stress generated into the silicon by different types of TiN barrier according to process parameters and subsequent plasma treatment were measured and compared (Figure 2). It comes out that some barriers induced a more compressive stress in the silicon and others seem to have a tensile behavior. Then the evolution of the stress of the TSV through different anneal conditions were studied to evaluate the stability of the via with the temperature.

This article is related to the development of a protocol for the characterization of the behavior of high aspect ratio through silicon via (TSV) during advanced three dimension (3D) integration. The time-of-flight (TOF)-SIMS profile measurement along the sidewall of the TSV with advanced samples preparations is described. This technique allows studying the efficiency of a low temperature, 200°C metallorganic chemical vapor deposition (MOCVD) titanium nitride (TiN) film as a barrier to copper diffusion into silicon. Then the thermo-mechanical stresses induced by the TSV in the surrounding silicon were studied by micro-Raman spectroscopy. Different TiN films were studied according to subsequent plasma treatments and compared with a reference deposited by ionized physical vapor deposition (i-PVD). The thermal stress in the silicon was found to decrease as a function of distance from an isolated TSV. The iPVD and MOCVD TiN barrier involved a more compressive stress than non-plasma treated MOCVD TiN.

This article is related to the development of a new low temperature CVD titanium nitride deposition process for the formation of a copper diffusion barrier in 3D TSV integration, using a metalorganic precursor and NH3.The physicochemical properties of the film are studied on 300 mm silicon wafers deposited using a SPTS Technologies Sigma300 fxP (TM) deposition equipment. A design of experiments (DoEs) was carried out at 200 degrees C to check the influence of parameters such as reactor pressure, spacing (distance between the showerhead and the wafer), precursor/NH3 flow rate during deposition and NH3 flow rate during a subsequent densification plasma treatment. Responses including resistivity, uniformity, deposition rate and stress were measured. From this DoE, two process points are chosen according to expected material specifications requested from applications: a low resistivity process and a median conditions process. Then microstructure, the composition and stoichiometry of the film deposited with these process points are studied. Finally, the step coverage and continuity of the barrier in a high aspect ratio "through silicon via" (8:1, 10 mu m diameter etched in 80 mu m silicon) are measured and compared with a reference I-PVD process. (C) 2014 Published by Elsevier B.V.

Co-implantation, with overlapping implantation projected ranges, of Si and doping species (P, As, and B) followed by a thermal annealing step is a viable route to form doped Si nanocrystals (NCs) embedded in silica (SiO2). In this paper, we investigate optical characterizations of both doped and un-doped Si-NCs prepared by this method. The effective NC presence in the oxide layer and their crystallinity is verified by Raman spectrometry. Photoluminescence (PL) and PL excitation measurements reveal quantum confinement effects and a gradual PL quenching with increasing dopant concentrations. In un-doped NC, the measured Stokes shift remains constant and its value similar to 0.2 eV is almost twice the Si-O vibration energy. This suggests that a possible radiative recombination path is a fundamental transition assisted by a local phonon. PL lifetime investigations show that PL time-decays follow a stretched exponential. Using a statistical model for luminescence quenching, a typical NC diameter close to 2 nm is obtained for As-and P-doped samples, consistent with our previous atomic probe tomography (APT) analyses. APT also demonstrated that n-type dopant (P and As) are efficiently introduced in the NC core, whereas p-type dopant (B) are located at the NC/SiO2 interface. This last observation could explain the failure of the luminescence-quenching model to determine NC size in B-doped samples. All together, these experimental observations question on possible different carrier recombination paths in P or As doped NC compared to B one's. (C) 2014 AIP Publishing LLC.

It is shown that co-implantation, with overlapping projected ranges of Si and P or As, followed by a single thermal annealing step is an efficient way to form doped Si nanocrystals (Si-nc's) embedded in SiO2 with diameters of a few nanometers. Atom probe tomography is used to image directly the spatial distribution of the various species at the atomic scale, evidencing that the P and As atoms are efficiently introduced inside the Si nanocrystals. In addition, we report on the influence of the dopant doses on the Si-nc's related photoluminescence as well as on the I(V) characteristics of MOS structures including these Si-nc's.

Co-implantation, with overlapping implantation projected ranges, of Si and of the doping species (P, As, or B), followed by a single thermal anneal step, is proved to be a viable route to form doped Si-nc’s embedded in SiO2, with diameters of a few nanometers. Extensive results of the evolution of the Si-nc’s related photoluminescence, as a function of the dopant implanted dose, are presented and discussed. Atomic Probe Tomography (APT) is used to image directly the spatial distribution of the various species at the atomic scale. The 3D APT data demonstrate that n-type dopant atoms (P and As) are efficiently introduced in the “bulk” of the Si-nanocrystals, whereas B atoms are preferentially located at their periphery, at the Si/SiO2 interface.

The effect of carbon codoping on boron distribution in implanted silicon has been investigated at the atomic scale using atom probe tomography. Whereas small boron-enriched clusters a few nm in size, containing about 2.4 at. % of boron atoms, are clearly visible in carbon-free B-implanted silicon after annealing at 800 °C for 30 min, no boron clustering is evidenced if C is coimplanted in the sample. C coimplantation is known to reduce the electrical deactivation of boron, but, in addition, this suggests that C addition induces a larger fraction of mobile boron near the peak of the B profile.