一般財団法人材料科学技術振興財団　MST List of Products and Services

In SSRM, we can obtain insights into local resistance, while in EBSD, we can gain knowledge about crystal grains and grain boundaries. By conducting SSRM measurements at the same location as the EBSD measurements, we measured the local resistance in areas that include crystal grain boundaries, which we would like to introduce.

By directly observing the junction interface using a Cs collector-equipped STEM device, it is possible to evaluate the crystal structure at the atomic level. In this study, we conducted HAADF-STEM imaging of the buffer layer/CIGS interface using Zn(S, O, OH) in the buffer layer of CIGS thin-film solar cells and evaluated the structure. As a result, it was suggested that the crystal structure at the junction is unclear compared to samples using CdS as the buffer layer, indicating that it is not an epitaxial junction.

Organic devices are devices that use materials susceptible to the effects of oxygen and water. At MST, we conduct analyses with sample transport, processing methods, and measurement environments that minimize atmospheric influences, allowing for evaluations closer to true conditions. We assessed the interface state between the organic film and the electrode using XPS analysis. We can confirm the composition and bonding state of the titania present on the surface of the organic film. Through TOF-SIMS analysis, we examined the dispersion state of P3HT (p-type organic semiconductor) and PCBM (n-type organic semiconductor) within the organic film of bulk and heterostructure organic thin-film solar cells in the depth direction.

For membranes with low density, it is difficult to achieve contrast at high acceleration voltages (hundreds of kV) due to the high transmission capability of the electron beam. However, in low acceleration voltage SEM-STEM images, slight differences in density can be reflected, allowing for clear composition contrast. This can be applied to organic EL films, low-k films, gate oxide films, TEOS films, BPSG films, etc., where the differences in density, average mass, and composition are small. 1) STEM observation using SEM equipment with lower acceleration voltage compared to dedicated TEM equipment. Measurement methods: TEM, SEM Product fields: LSI, memory, display, solar cells, lighting Analysis purposes: Shape evaluation, film thickness evaluation For more details, please download the materials or contact us.

In the pursuit of improving the efficiency of CIGS thin-film solar cells, various buffer layer materials have been investigated for controlling the band structure and crystallinity from the light absorption layer to the transparent electrode. This presents a case study of various evaluations conducted using X-rays on Zn-based buffer layers deposited on a flattened substrate. Comparisons can be made between different levels based on deposition conditions and various processes after deposition.

Polycarbonate (PC) is a type of thermoplastic that has excellent transparency, impact resistance, and heat resistance. It has been reported that degradation occurs due to hydrolysis, leading to the generation of the raw material bisphenol A (BPA). Particularly in solar panels, it is important to understand how the surface of the material changes under UV (ultraviolet) irradiation. Below, we present a case study that evaluated the degree of degradation of the PC surface due to UV irradiation using TOF-SIMS.

Tetramethylammonium hydroxide (TMAH) is used as a developing solution and etching solution in semiconductors. When measuring the concentration of TMAH solution used in Si etching solutions, the large amount of dissolved Si can become an impurity and affect the measurement results. However, evaluation using the IC (ion chromatography) method allows for quantitative analysis of TMAH concentration without being influenced by Si.

Polycarbonate (PC) is a type of thermoplastic that has excellent transparency, impact resistance, and heat resistance, and is widely used as a material for solar panels, eyeglass lenses, CDs, automotive parts, and medical devices. In this study, TOF-SIMS analysis was conducted using GCIB (Ar cluster) with a sputter ion beam to evaluate the degradation layer on the surface of PC. *Note: GCIB stands for Gas Cluster Ion Beam.*

- Photoluminescence measurement (PL measurement) can be conducted not only at room temperature but also by placing the sample in a cryostat for low-temperature measurements. Low-temperature measurements tend to show an increase in peak intensity and a decrease in peak full width at half maximum compared to room temperature measurements, which may provide insights into various energy levels. - Below, we will explain the precautions for low-temperature measurements and the differences in spectral shapes between room temperature and low-temperature measurements.

In semiconductor devices, their performance is greatly influenced by the combination of work functions of various materials that make up the device. Therefore, attempts have been made to control the work function through surface treatments and modifications, and it is important to verify their effects. This document presents an example of evaluating the change in work function of ITO (Sn-doped In2O3), used as an electrode material in organic ELs and solar cells, before and after surface plasma treatment using UPS analysis.

In XPS analysis, the binding state evaluation of the material surface is conducted by observing the energy of photoelectrons obtained through X-ray irradiation. It allows for the assessment of whether metal elements are in an oxidized state, and for elements with significant energy shifts (chemical shifts) due to oxidation, it also enables the evaluation of the presence and proportion of multiple valences. Below are the main metal elements and oxides for which multiple valence evaluations are possible.

Self-assembled monolayers (SAMs), which are oriented organic films, have their functions and properties, such as surface wettability and adsorption, altered by orientation and orientation angle. Using XAFS with synchrotron radiation, it is possible to evaluate the orientation and orientation angle of organic film materials by analyzing the X-ray incidence angle dependence of peak intensity.

The electron diffraction method using an electron microscope is classified into three types based on the way the electron beam is incident on the sample. The characteristics of each type and examples of data are presented. It is necessary to choose the appropriate method according to the size of the evaluation object and the analysis purpose.

In the fabrication of Si-based semiconductor devices, various processes such as ion implantation and annealing are performed. It is considered important to confirm the degree of irradiation defects and the extent of crystallinity recovery before and after these processes in order to control the manufacturing process. Photoluminescence (PL) measurements at low temperatures are one effective means of investigating these aspects. An example of PL measurements of samples that underwent ion implantation on a Si substrate followed by annealing treatment is presented.

Silicon oxide films are widely used as gate dielectrics in MOS devices and as anode materials in lithium-ion secondary batteries, but it is known that the presence of intermediate oxides and the bonding states at the interface have a significant impact on device characteristics. XAFS measurements using synchrotron radiation can detect information from a depth of several tens of nanometers from the sample surface, allowing for non-destructive analysis of the structure and bonding states in both bulk and at the interface. This document presents a case study investigating the presence of intermediate oxides in silicon oxide films using XAFS.

Insights into the relationship between electrical properties and crystals can be obtained through EBIC and EBSD, but the depth of information differs. For areas where electrical properties were characteristic in the EBIC distribution measurement, we created cross-sectional samples and conducted STEM imaging in the depth direction. Additionally, we measured electron diffraction for each crystal grain. This further clarified the relationship between electrical properties and crystal grains and grain boundaries. By performing STEM observation and electron diffraction measurements, it is possible to obtain localized information about specific crystal grains.

By using low-energy STEM observation and STEM-EELS surface analysis, we evaluated the mixed state of the active layer in bulk heterojunction solar cells. For the evaluation, samples were prepared with only the active layer deposited on ITO. The contrast in the low-energy STEM image (Photo 1) corresponds to the elemental distribution of S and C in the STEM-EELS images (Photos 2 and 3), confirming that it reflects the bulk heterostructure. Additionally, a bias in the distribution of S was observed, suggesting that P3HT is segregated towards the surface side.

We directly observed the CdS/CIGS heterojunction interface using a Cs-corrected STEM device. TEM images, high-resolution HAADF-STEM images, and simulations using first-principles calculations confirmed that CIGS and CdS are heteroepitaxially joined.

The heterojunction interface of ZnO/CdS/CIGS in CIGS thin-film solar cells was analyzed using the SSRM method, and the local resistance distribution was measured. By conducting measurements in a vacuum environment, we were able to remove adsorbed water from the measurement surface and achieve high spatial resolution. The measurement results indicate that we can measure the resistance values of each layer with nanometer-level spatial resolution. The resistance values of each layer differ by several orders of magnitude, indicating differences in carrier concentration. It was found that the CIGS layer has a higher resistance than the i-ZnO layer, and that CdS has an even higher resistance than these layers.

In bulk heterojunction solar cells using p-type and n-type material active layers, it is necessary to properly control the mixing state of the materials within the film. After performing annealing treatment post-deposition, we conducted TOF-SIMS depth profiling analysis on samples that showed an improvement in photoelectric conversion efficiency along with an increase in fill factor without any change in open-circuit voltage. As a result, it was found that PCBM was segregated at the interface with the PEDOT:PSS layer before annealing.

We investigated the distribution of the blue pigment "Cu phthalocyanine" dispersed on the polyethylene surface. TOF-SIMS analysis allows us to capture the distribution of organic materials with a pigment size of 1μm.

This paper introduces a method for evaluating the in-plane distribution of solar cells with surface roughness while avoiding the effects of the roughness, using cross-sectional samples assessed by imaging SIMS. It was found that in regions identified as p+ Si layers by cross-sectional SCM, B and Al were present in high concentrations. Furthermore, using line profiles, the dopant distribution was converted to concentration, quantifying the degree of inhomogeneity in the plane. This method can also be applied to deep junction evaluations of power devices and impurity distribution assessments between and within trenches. Measurement methods: SIMS, SCM, SNDM Product field: Solar cells Analysis objectives: Trace concentration evaluation, composition distribution evaluation, shape evaluation For more details, please download the materials or contact us.

CIGS thin-film polycrystalline solar cells are expected to be low-cost next-generation solar cells. Development is underway for large-area and high-quality production. To evaluate the characteristics of the polycrystalline thin film, we conducted assessments of the pn junction using EBIC and crystal grain evaluation using EBSD on the same cross-section. We prepared a cross-section of the CIGS film and measured the open-circuit voltage (EBIC) by scanning an electron beam, visualizing the in-plane distribution of the open-circuit voltage. Additionally, by measuring EBSD on the same surface, we correlated the distribution of the open-circuit voltage with the crystal grains.

In solar cells, surface roughness is utilized to effectively absorb sunlight. When conducting SIMS analysis, the surface roughness leads to a decrease in depth resolution. Measurements from the surface appear to show that elements like Cd, Zn, and O are diffusing into the CIGS layer due to the effects of surface roughness and knock-on (Figure 3), but measurements taken from the substrate side (back side) reveal that there is no significant diffusion of Cd, Zn, and O into the CIGS layer (Figure 4). In addition to interdiffusion, it is also possible to evaluate changes in the composition of the main components (Cu, In, Ga, Se) and the concentration distribution of impurities (B, Na, Fe).

CIGS thin-film polycrystalline solar cells are being developed as next-generation solar cells expected to achieve low cost, large area, and high quality, and crystal information is required in this process. The EBSD method allows for the evaluation of crystal grains in CIGS films. The crystal information obtained from the EBSD method mainly includes orientation and grain size.

In bulk heterojunction solar cells using mixed films of p-type and n-type materials, it is necessary to appropriately control the mixing state of the materials within the film for high efficiency. In films with low density (such as organic films), it is difficult to achieve contrast using a dedicated TEM machine at high acceleration voltages (several hundred kV) due to the high transmission of the electron beam. On the other hand, in STEM imaging at low acceleration voltages, where slight differences in density are reflected, the mixing state within the film can be clearly observed.

The uniformity of the film composition and the distribution of impurities, which are one of the elements in device creation, were evaluated using imaging SIMS analysis. Through data processing after measurement, we can obtain planar images (Figure 1), cross-sectional images (Figure 2), depth distribution profiles at arbitrary locations (Figures 3 and 4), and line profiles. From the distribution of constituent materials and impurities, we can gain information that leads to process and film quality improvements.

We conducted TOF-SIMS analysis on an organic EL device (Figure 1) estimated to be formed from four layers of different organic compounds (or organometallic complexes) using XPS. For multilayer structural samples, depth profiling analysis using sputtering is also performed; however, in this case, we created a slope surface to expose each layer without breaking the bonds of the constituent components. Molecular weight-related ions and fragment ions presumed to be Alq3, NPD, and CuPc were obtained, confirming that TOF-SIMS analysis of the slope surface is an effective method for component analysis of organic multilayer films.

Measurements can be performed in bulk state without the need for thinning processes like TEM (NBD: Nano Beam Diffraction). It has the high spatial resolution characteristic of SEM and relatively high strain sensitivity. Additionally, there is a possibility of detecting local lattice strain as tensor data.

It is possible to directly extract small pieces from the sample (micro-sampling) and perform FIB processing.

When light with energy greater than the bandgap of a solar cell is irradiated, carriers are generated, and some of them undergo radiative recombination. The light emitted during this process is called photoluminescence (PL). However, in areas where defects are present, carriers are trapped, resulting in reduced PL intensity. Therefore, by conducting PL mapping measurements, it is possible to non-destructively and easily identify defect locations. Below is an example of identifying defect locations through PL mapping measurements in multicrystalline silicon solar cell modules.

This is an example of quantitatively evaluating the dopant concentration distribution directly beneath the electrode in back contact type crystalline silicon solar cells. Additionally, by evaluating the carrier distribution, it is possible to determine the polarity of p/n and visualize the depletion layer in the cross-sectional direction.

We propose a method for evaluating the control of impurity levels required in each process from substrate growth to cell formation of crystalline silicon solar cells, using high-sensitivity analysis for element concentration measurement. Metal elements can be measured at concentrations below ppb, and atmospheric component elements containing hydrogen can be measured at concentrations below ppm. Measurement methods: SIMS, ICP-MS, etching, disassembly Product field: Solar cells Analysis purpose: Trace concentration evaluation, product investigation For more details, please download the materials or contact us.

This is an introduction to a case where the carrier diffusion layer distribution of the surface textured part and the back surface field (BSF) part of BSF-type crystalline silicon solar cells was evaluated using SCM. In the textured part, the pn junction is formed along the surface irregularities, while in the BSF part, it can be confirmed that the carrier distribution is interrupted and uneven.

We will introduce a case where the concentration distribution of dopants in a-Si (amorphous silicon) was quantitatively evaluated in flexible thin-film Si solar cells. The sample, sealed with resin, was disassembled, and SIMS analysis was conducted. In the analysis of B (Figure 3), measurements were performed with enhanced depth resolution because it exists in shallow areas on the surface side. In the analysis of P (Figure 4), a large amount of H exists in a-Si, causing mass interference; therefore, measurements were conducted under conditions that separated H from Si using high mass resolution methods to detect only P.

It is possible to non-destructively determine the interstitial oxygen and carbon atom concentrations in silicon single crystals using FT-IR analysis. The concentrations are calculated from the peak heights of the absorption due to interstitial oxygen or carbon in the spectra measured by the transmission method. The calculation method is standardized by the Japan Electronics and Information Technology Industries Association (JEITA). Below are examples of calculated interstitial oxygen atom concentrations.

In the development aimed at enhancing the performance of CIGS thin-film solar cells, the optimization of the film formation process conditions for the light-absorbing layer is necessary, and controlling the compositional distribution of the CIGS composition has become important. This document presents cases where the composition of the deposited CIGS thin film was quantitatively analyzed with high precision using ICP-MS, evaluated for depth concentration distribution using SIMS, and assessed for in-plane concentration distribution on the substrate using XRF. Measurement methods: SIMS, ICP-MS, XRF, etching Product field: Solar cells Analysis objectives: Composition evaluation, identification, compositional distribution assessment, film thickness evaluation, product investigation For more details, please download the materials or contact us.

In the development aimed at achieving flexibility and cost reduction for CIGS thin-film solar cells, low-temperature formation processes for the light-absorbing layer and non-vacuum processes are required, making the optimization of the film formation method for CIGS composition and the control of metal contamination levels crucial. This time, we will introduce a case where the composition and impurity concentration of the raw CIGS powder were evaluated with high precision using ICP-MS.

By using a Cs-corrected TEM device that compensates for spherical aberration, it is possible to observe the cross-sectional structure of devices with high resolution. This case presents data from high-resolution (HR)-STEM observation and EDX elemental distribution analysis of the light-absorbing layer of CIGS thin-film solar cells. In CIGS, which has a polycrystalline structure composed of four elements, atomic resolution EDX analysis was performed, visually revealing the distribution of atoms.

For the sample where Pt was sputter-deposited on a Si substrate, Out-of-plane XRD and In-plane XRD measurements were conducted while increasing the temperature. In both measurements, it was observed that the peak intensity of Pt(111) increased and the full width at half maximum decreased at temperatures above 500°C, indicating that crystallization was progressing. Additionally, it was confirmed that as the temperature rose, thermal expansion caused the peaks to shift towards lower angles (the direction of increased lattice spacing).

The band gap of thin film samples has been measured using analytical methods such as UV-Vis, PL, and XPS, but the cases that could be evaluated were limited due to constraints related to the sample structure, such as materials, film thickness, and substrates. This time, through the combined analysis of XAFS and XPS, it has become possible to reduce the constraints of the sample structure and achieve a higher precision band gap evaluation than before. This method is particularly effective for the evaluation of various oxide and nitride films. This document presents a case study on the band gap evaluation of silicon nitride (SiN) films. Measurement methods: XAFS, XPS. Product fields: solar cells, lighting, oxide semiconductors, power devices. Analysis purpose: evaluation of electronic states. For more details, please download the document or contact us.

When ions or electron beams are irradiated onto Si, a portion of the "substitutional carbon" that is slightly contained in Si changes into "interstitial carbon." This interstitial carbon is believed to influence the electrical properties of the device. The behavior related to interstitial carbon can be observed very sensitively through low-temperature PL analysis, allowing insights into trace amounts of carbon below the detection limit of SIMS analysis. This document presents examples of low-temperature PL analysis and SIMS analysis conducted on Si substrates subjected to ion implantation.

The SIMS analysis profile of the interface between different materials changes with a certain width in the depth direction. This is due to the characteristics of SIMS analysis, which are influenced by ion beam mixing and the roughness of the sputtered surface. The detected impurities represent averaged information up to the mixed depth, detecting ions from regions with a width in the depth direction. Therefore, the interface position is generally defined as the location where the ion intensity of the main constituent elements reaches 50%.

In clean rooms where the manufacturing of semiconductors and liquid crystals takes place, it is important to monitor not only particles but also molecular-level chemical contamination (molecular contamination). Floating molecular contaminants include acidic and basic gases, cohesive organic substances, dopants, and metals, and the analysis methods vary depending on the components. Here, we will introduce details about cohesive organic substances and the representative collection methods, "adsorbent collection" and "wafer exposure collection."

The peaks in the Raman spectrum of single crystal Si shift to higher wavenumbers when compressive stress is applied to the sample and shift to lower wavenumbers when tensile stress is applied. This allows us to gain insights into the stress in Si. An example is shown where the distribution of stress in the cross-section of an IGBT (Insulated Gate Bipolar Transistor) was confirmed using Raman mapping.