Semiconductors

Phosphor plays a key role to obtain white light as for blue LED + phosphor and near ultraviolet LED + phosphors. In order to improve high bright white LEDs, it is necessary that the whole phosphor particle emits light homogeneously. When measuring with CL the phosphor used as white LED, the area which does not emit light in phosphor particle can be observed. CL system is used for evaluation of non-luminescent area to improve luminescent efficiency and characteristics.

Phase Modulated Spectroscopic Ellipsometry is an excellent technique for the highly accurate characterization of complete TFT-LCD device. The technique allows the determination of film thickness, optical properties but also more complex properties such as graded or anisotropic layers and effect of dopants. In the flat panel industry the pressure to reduce manufacturing coasts is and reliable metrology tools are required to control the different steps of the process. Spectroscopic ellipsometry is a non-destructive technique which presents advanced capabilities and proven reliability tailored for qualification and on-line production control.

Raman spectroscopy is a very well suited technique to determine both Ge fraction and strain in SiGe layers and Si cap layers. Moreover the possibility of using both UV and visible excitation lines on the same instrument is essential to study structures made up of a Silicon cap layer on top of a SiGe layer. The relative Ge content in the constant Si1-xGex layer is calculated from the visible Raman spectrum and the strain of the cap Si layer is derived from the UV Raman spectrum.

Liquid Crystal Modulation Spectroscopic Ellipsometry is an excellent technique for the highly accurate characterization of the compound semiconductor heterostructure AlGaN / GaN. Using the MM-16 spectroscopic ellipsometer it is a straightforward procedure to determine the film thickness and optical dispersions of the complete structure even where the film is several microns thick. The detailed knowledge of the optical parameters of AlGaN alloys is crucial for example for the design of opto-electronic devices. Furthermore, from the optical parameters a calibration curve could be constructed to provide a rapid and efficient determination of the Al content in the AlGaN layers. Thus Spectroscopic Ellipsometry also proves a non-destructive technique for AlGaN alloy composition determination. This method can be equally applied to other compound emiconductors such as SiGe, II-VI semiconductors or classical III-V semiconductors.

The abrasive particles found in CMP slurries have a size distribution which directly affects critical metrics. Particle size analysis is therefore a key indicator of CMP slurry performance. The popularity and utility of several particle sizing techniques will be discussed within.

PP-TOFMS is a fast and reliable technique for depth profiling of rare earth doped ZnO thin films. Tb and Eu profiles are obtained with high sensitivity and high depth resolution. This type of information is typically provided by SIMS, RBS or depth profiling XPS but not as rapidly and readily and at a higher cost. Such profiles turn out to be powerful complementary information to understand photoluminescence data. This example extends to similar materials for photonics (lighting, display, solar energy industries) applications such as other wide bandgap semiconductors (SiC, GaN...), nitrides and oxynitrides layers, silicon nano-objects, glasses... doped with Yb, Y, Sm, Er, Nd, Pr, and Tm...

UVISEL ellipsometers have been used for the characterization of several systems of nanoparticles. This ellipsometric characterization involves the development of specific modeling tools available within DeltaPsi2 software. Through this report we illustrate the application of ellipsometry to the characterization of nanoparticle based samples. Our goal is to demonstrate that the technique can apply within a large panel of materials science. The HORIBA ellipsometric product line offers the most versatile hardware of the UVISEL series combined with the DeltaPsi2 software including unique modeling features to get the most of your applied work on this fascinating domain of modern physics.

Spectroscopic ellipsometry is a powerful technique to characterize the thickness and optical constants of complex ferroelectric stacks with high accuracy and precision. Specific modelling features in this study include the characterization of the anisotropic sapphire substrate, rough overlayer and layer inhomogeneity with depth.

In this work, spectroscopic ellipsometry (SE) was successfully applied to characterize the optical properties and the thicknesses of doped and undoped diamond layers. The sensitivity of this technique enables the doped layer to be distinguished from the undoped one in a sample consisting of a stack of these two layers. Moreover, an interface between the two layers has been detected. This work and others reported previously show clearly that ellipsometry is the technique of choice for the characterization of optical and structural properties of layered materials thanks to its sensitivity and the wide range of information it provides.

For multilayer structures it is always helpful and often necessary to know the properties of each film. Using the Jobin Yvon UNISEL NIR it is a straightforward procedure to investigate the thickness and optical properties of the complete PDP structure. To ensure high yields in quality and quantity the FF-1000 ellipsometer is dedicated to the flat panel industries with a fully automated large area sample stage able to accept samples up to 1000 mm x 1000 mm. This accurate, automated thin film metrology tool delivers both unique performance and proven reliability for online quality control of production processes.

We have performed a complete Raman polarized study of a single GaN nanowire using a confocal microscope together with a high resolution stage. The high spatial resolution of our Raman confocal instrument together with a piezoelectric stage demonstrates unambiguously the possibility to image the optical properties of nano-objects with a resolution better than 200 nm keeping the fill advantage of the polarization control under a confocal microscope.

Spectroscopic ellipsometry is a powerful technique for high accuracy characterization of the thickness and optical constants of GeSbTe multilayer system for rewritable optical disc applications. It was shown that measurement in the NIR range gives better accuracy for the analysis of these types of material. The use of the multiple sample analysis reduces parameter correlations and errors for the thinnest layers. Owing to the advanced modeling features included in the DeltaPsi2 software, it is a straightforward procedure to analyze such structures even with layers deposited on both sides of the substrate.

Spectroscopic Ellipsometers are optical thin film measurement tools for determining film thickness and optical constants (n,k) of thin film structures. They are widely used in the microelectronics, display, photonics, photovoltaics, lighting, optical and functional coating, biotechnology industries. When compared with other optical metrology instruments the unique strength of spectroscopic ellipsometers are based on their highly precise and simple experimental measurements plus physical and material information derived from optical constants characterization.

Phase Modulated Spectroscopic Ellipsometry is an excellent technique for the highly accurate characterization of complete OLED stacks. The technique allows the determination of film thickness, optical properties and the effect of dopants to the active layers. For very high throughput applications where large area flat panels are to be characterized in a production environment the Jobin Yvon FF-1000 ellipsometer has a fully automated sample stage able to accept samples up to 1000 mm x 1000 mm. This accurate, automated thin film metrology tool delivers both unique performance and proven reliability for on-line quality control of production processes.

The characterization of synthetic CVD diamond material by hyperspectral cathodoluminescence spectroscopy and imaging allows the detection and accurate location of the promising NV luminescent point defects for innovative solid-state quantum mechanical systems. In this work we performed CVD epitaxial growth on a pattern of micro-pillars etched on a diamond substrate. Cathodoluminescence (CL) analysis revealed that NV centres were successfully localized at the edges of the pillars.

High-k dielectrics are under investigation to replace the conventional SiO2 or SiOxNy gate dielectric in many applications of Complementary Metal Oxide Semiconductor (CMOS) devices. Hafnium aluminium oxides (HfAlO) were investigated in this study as they fulfill the physical properties required for such applications. The structure and composition of hafnium aluminate films as well as the HfAlO / Si interface play a very important role for the optimization of CMOS devices. For this study complementary optical techniques were used. VUV Spectroscopic ellipsometry and infrared spectroscopy (FTIR-ATR) provide accurate characterization of thin film thickness and optical properties near and above the bandgap.

In this Application Note Spectroscopic Ellipsometry, a standard optical characterization technique used to measure multi-layered thicknesses and optical constants (n,k), has been successfully used to characterize encapsulated OLED devices. This report also investigates the aging process of OLED. Spectroscopic ellipsometry is a powerful technique to characterize the thickness and optical constants of encapsulated OLED devices. For the case of non-transparent encapsulation the combination of ellipsometric measurements via the glass substrate and the powerful modelling features of DeltaPsi2 software make it possible to analyze “this reverse sample”.

The threading dislocation occurs easily in GaN crystal grown on sapphire substrates. It is said that this is caused by the large lattice mismatch of sapphire and GaN. The crystal may seem to be uniform in the SEM image, but the dark spot such as the threading dislocation can be observed when measuring the CL intensity image at the wavelength (362nm) which corresponds to the band edge emission.

Spectroscopic ellipsometry is an excellent technique for the highly accurate characterization of TFT-LCD display panels based on a-Si and LTPS technologies. Owing to the sensitivity of the UVISEL spectroscopic ellipsometer and the advanced modeling features included in the DeltaPsi2 software it is possible to detect in a multistack different a-Si layers processed by various methods. Moreover the spectroscopic ellipsometry measurements allow determination of the grain size of p-Si films and illustrate the ability to characterize the crystallinity of silicon with high accuracy.

OLED technology is playing an important role in display technology since it offers several advantages compared to LCD technology among which its efficiency and high display quality, a high contrast rate, lower energy consumption, etc. Furthermore, this technology has an ecological aspect since it uses organic recyclable materials. However the improvement of the performances of the devices produced by these technologies requires a precise knowledge of their optical and structural properties that could be provided by spectroscopic ellipsometry. This non destructive and sensitive optical technique is able to characterize layers with thicknesses of some angstroms and provides information regarding the state of the surface, the microstructure of composite materials, etc.

Driven by applications like LED-backlit TVs and solid-state lighting, the global LED market is growing rapidly. The main challenges for general LED lighting include reducing overall production costs and increasing efficiency and lifetimes. The performance of a LED which is characterized by its wall-plug efficiency depends on the design and overall material properties of the LED thin film structure. Ellipsomentry may be used for the accurate determination of the thickness and optical constants of the LED device for both research and industrial applications. Accurate control of thickness and refractive index is vital for the optimization of device properties and for industrial quality control.

Hybrid organic-inorganic perovskite materials have emerged over the past five years as promising absorber layers for new high-efficiency and low-cost solar cells that combine the advantages of organic and inorganic semiconductors. The increasing interest in this technology is pushing research laboratories to find the optimal techniques for the accurate characterization of opto-electronic properties of these materials.

Both TEPL and TERS images are well correlated with AFM morphological images obtained simultaneously, and all are consistent in revealing the nature (number of layers) of MoS2 flakes. Upon deconvolution, the TEPL signal is even capable of revealing local inhomogeneities within a MoS2 flake of 100 nm size. Kelvin probe measurement supports TEPL and TERS measurements and adds to the power of such tip-enhanced combinative tools. TEOS characterization of 2D materials is likely to contribute to further deployment of these materials into commercial products through a better understanding of their electrical and chemical properties at the nanoscale.

Raman and photoluminescence spectroscopy reveal different aspects of the solid state structure of 2D materials. Raman and photoluminescence imaging performed simultaneously with one instrument reveals the spatial variation of the solid state structure and electronic properties of 2D crystals that is not revealed in reflected white light imaging. That ability should allow materials scientists to better design and fabricate electronic and optoelectronic devices based upon 2D crystals.

The use of TERS to reveal the defects density in the structure of CNTs is of interest for a better understanding of the electrical properties of the devices made with such nano-objects. Not only defects concentration but also local chirality changes from the different radial breathing modes, pressure effect and strain distribution can be studied at the single carbon nanotube level through TERS.

The two methods - Analysis of fingerprint modes (intralayer) and Analysis of low-frequency modes (interlayer) - give complementary results and allow the determination of the number of MoS2 layers. Method 2 (using low frequency modes) gives excellent contrast; however it does not show single layer regions (which is related to the nature of the modes, rising from interaction between at least two layers). Method 1 (using fingerprint modes) shows all the layers, but the contrast is poorer, particularly for higher numbers of layers. The best result can be obtained combining the two methods. All the measurements (low-frequency and fingerprint) were done using ultra-low frequency ULFTM filters which allow a high throughput measurement in a full Raman range, down to <10 cm-1.

Spectroscopic ellipsometry (SE) is used to determine the optical constants of C60 and C70 thin films over the range 0.6-6.5eV (i.e. 190-2100nm). The information provided by the optical constants allows for a better understanding of the electronic structure of these materials.

The UVISEL Spectroscopic Ellipsometer is the ideal tool for reliable film thickness and optical constants characterization of amorphous carbon coatings, even in difficult cases where the film thickness is very thin. Roughness, and interface "adhesion" can also been determined.

Raman has shown a high potential in characterising the SWCNTs' structure. The correlation between knowledge about structure with physical and chemical properties about the tubes make the technique extremely powerful to control the quality of the SWCNTs for specific applications. Raman spectrometer capabilities like spatial resolution, spectral resolution and excitation wavelength versatility have been examined. Beside Raman, preliminary fluorescence studies are describing the potential of the technique.

The Raman spectra of the various forms of elemental carbon are very sensitive to the type of nearest neighbour bonding, and to intermediate and long range order. In many cases Raman spectroscopy is the technique of choice for characterization of carbon materials. Correlation of Raman spectral features with tribological properties can facilitate the deposition of carbon films.

Graphene is a new nanomaterial which may partially replace silicon in microcircuits and computer chips in the future. In order to better understand its quality characteristics, fast reliable techniques that deliver the right property measures are needed. Raman spectroscopy has emerged as a key technique for studying this exceptional material.

In this work, spectroscopic ellipsometry (SE) was successfully applied to characterize the optical properties and the thicknesses of doped and undoped diamond layers. The sensitivity of this technique enables the doped layer to be distinguished from the undoped one in a sample consisting of a stack of these two layers. Moreover, an interface between the two layers has been detected. This work and others reported previously show clearly that ellipsometry is the technique of choice for the characterization of optical and structural properties of layered materials thanks to its sensitivity and the wide range of information it provides.

The Raman spectra of elemental carbon materials are known to be sensitive to polymorphy. For hard carbon films, the spectra of amorphous and diamond-like carbons can be band-fit to separate the contributions of the "graphitic carbon" (G band) from the "disordered carbon" (D band). The spectral behaviour of carbon films has been empirically correlated with thin film physical properties such as hardness, durability, optical transparency, electrical conductivity, thermal conductivity and corrosion resistance, and can be of use for prediction of these properties without extensive alternative testing. The DiskRam has been designed to automate the collection of Raman spectra from hard carbon coatings on computer hard disk media and the extraction of parameters that are well correlated with the properties of the films. The extracted information is output in spreadsheet format for SPC at a manufacturing facility.

The colour enhancement treatment on native brown and yellow diamonds can be highlighted by Photo Luminescence analyses performed with the Raman spectrometer LabRAM HR. The PL signature of green and violet diamonds has also been recorded. The defect centres responsible of the colour of the diamonds have all been detected and assigned. This proves the Raman spectrometer to be a very good tool to investigate the fine defects in the Diamond structure by Photoluminescence analysis.