E-beam Evaporation Technique Research Articles

Dark-field microscopy studies of single silicon nanoparticles fabricated by e-beam evaporation technique: effect of thermal annealing, polarization of light and deposition parameters.

Herein, we report the dark-field microscopic studies on single silicon nanoparticles (SiNPs) fabricated using different deposition parameters in the electron beam (e-beam) evaporation technique. The morphology of the fabricated SiNPs is studied using the Atomic Force Microscope. Later, for the first time, the effect of thermal annealing and deposition parameters (i.e., beam current and deposition time) on the far-field scattering images and spectra of single SiNPs is studied using a transmission-mode dark-field optical microscope to estimate the wavelength locations and full-width at half maxima of the optical resonances of single SiNPs. Finally, the role of polarization of incident light on the optical resonances of single SiNPs is also studied by recording their scattering images and spectra.&#xD.

Investigation of laser-assisted micromachining of NiTi SMA bimorph based actuators toward developing optical shutters

Abstract This work explores laser-assisted micromachining for the precision cutting of NiTi shape memory alloy (SMA)-based bimorph in a single-pass laser scan. SMA thin film based optical shutters were developed with this method, which can generate the opening and closing via Joule’s heating rather than mechanical components. NiTi SMA bimorph was fabricated using the e-beam evaporation technique followed by micromachining using a 1064 nm fiber laser. The influence of laser power (LP), laser speed (LS), spot diameter (SP), and laser travel direction on kerf width and heat-affected zone after micromachining was studied using the design of experiments. The optimized parameter for micromachining was at LP 5 W with 5 mm s−1 LS and 50 μm SP. Various shapes were cut at the optimized parameter, including an optical shutter of a diameter of 30 mm. A LS of 6 mm s−1 has produced microchannels in the bimorph due to NiTi film removal only. The SEM analysis of the shutter reveals the formation of refined grains at micromachined edges compared to the center of the actuator. Fabricated optical shutter shows negligible optical transmittance in the 450–700 nm wavelength range.

Synthesis and characterization of Co3O4 spinel nanowall: understanding the growth mechanism and properties

Formation of spinel tricobalt tetraoxide (Co3O4) nanostructures through a controlled thermal oxidation process is discussed here. Thin films of high purity cobalt (Co) were deposited on glass/quartz substrates using an electron beam (E-beam) evaporation technique. Thermal oxidation of the as-deposited Co thin films was carried out at various oxidation temperatures (400 °C to 600 °C) for different durations (5 h to 15 h) to grow various oxide nanostructures. Different surface characterizations techniques were used to investigate the structure, chemistry and electronic properties of the as-grown cobalt oxide nanostructures. x-ray diffraction analysis revealed the presence of the CoO phase along with the Co3O4 phases at relatively lower oxidation temperature. However, the Co3O4 phase becomes more predominant for longer oxidation durations at higher oxidation temperatures. Field emission scanning electron microscopy analysis showed a surface morphological transition from nanowalls to nanograins with an increase in the oxidation temperature. The surface electrical conductivity of the oxidized Co films is also increased for higher oxidation temperature and/or duration mainly due to the oxide phase purity and larger particle sizes. Ultraviolet–visible spectroscopy indicated two distinct optical energy bandgaps, which effectively decreased with an increase in the oxidation temperature and duration. Raman spectroscopy identified five different Raman-active modes corresponding to the Co3O4 phase, with the F2g mode dominating at higher temperatures. All these findings provide clear insights into the structural, electrical, chemical and optical properties of cobalt oxide thin films. Moreover, it provides a mechanism on how to grow 2D nanowalls morphology of Co3O4 films which can further be used in energy, sensor or catalytic applications.

Photovoltaic properties of Cu(In,Ga)(Se,Te)2 thin film solar cells with different tellurium amounts and a copper-poor stoichiometry

In this study, the impact of tellurium addition on the microstructure of the copper indium gallium selenide absorber layer with a copper-poor stoichiometry and the photovoltaic properties of SLG/Mo/CIGS/CdS/ZnO/ITO/Ni-Al-Ni solar cells was investigated. Absorber layer, CdS buffer, ZnO and ITO layers, and the Ni-Al-Ni front contact were produced using three-stage co-evaporation, chemical bath deposition, RF magnetron sputtering, and e-beam evaporation techniques, respectively. The thickness and the composition of the absorber layer were controlled in situ. NaF post deposition treatment were applied to the absorber layer. The addition of tellurium improved the crystal quality by increasing the average grain size and decreased the surface roughness. Decreasing surface roughness increased reflection and thus decreased the amount of sunlight absorbed, which in turn reduced current collection. Open-circuit voltage was effected by impurity level and the grain boundry recombination. While moderate tellurium addition reduced grain boundary recombination, excessive tellurium addition created stress, caused crack formation, and increased recombination by reducing crystal quality. The optimum tellurium amount in the copper-poor CIGS structure was found to be 1.1 atomic percent. The control of the microstructure of the absorber and the efficiency improvement of the solar cell were achieved successfully.

Self-powered photodetector based on Cu2O thin film fabricated using E-beam evaporation technique

Self-powered photodetector based on Cu2O thin film fabricated using E-beam evaporation technique

Effect of annealing on magnetic and magnetocaloric properties of SmCo3B2 thin films

In this study, SmCo3B2 ternary thin films of manifold thickness were fabricated via e-beam evaporation technique. All the as-deposited SmCo3B2 thin films were subjected to electron beam rapid thermal annealing (ERTA). The X-ray diffraction studies showed amorphous nature for all the as deposited thin films and a highly crystalline hexagonal structure for all ERTA subjected thin films. The elemental composition, purity and surface morphology of the samples were analyzed using energy-dispersive x-ray spectroscopy (EDS) and High-resolution Scanning Electron Microscopy (HR-SEM). Furthermore, the study investigates the magnetocaloric properties of SmCo3B2 thin films, with significant changes depending on the thickness and annealing time. The thin films exhibited a magnetic phase transition around the Curie temperature (Tc) within the range of 40–46 K, attributed to the indirect exchange coupling of Sm–Sm sublattice interactions. Moreover, a significant shift in Tc towards higher temperatures with respect to thickness and annealing were observed in both as deposited and ERTA subjected thin films. The Arrot plots in the positive quadrant suggested the second order magnetic phase transition (SOPT) for all the films. The maximum magnetic entropy change (−ΔSm) of 1.172 Jkg−1K−1 accompanied by a relative cooling power of 5.33 Jkg-1 was achieved for 240 nm ERTA subjected thin film under a change in magnetic field of 5T. The study reveals the effect of ERTA and thickness dependent magnetic and magnetocaloric properties of SmCo3B2 thin films.

Detection of H2O2 using Carbon Nanotubes Covalently Attached to Nanostructured Au Electrode

Detection of hydrogen peroxide (H2O2) has practical significance in various fields, including pharmaceutical, clinical and food industries. The enzyme based H2O2 biosensors allow for the detection at lower potentials, thus avoiding possible interference from reducing agents. However, this type of sensors is inherently less stable, difficult to fabricate and more expensive. Due to high electroactive surface area and electrocatalytic properties, gold nanoparticles and their combination with carbon nanotubes (CNTs) are commonly used in H2O2 sensor design.To avoid fabrication inconveniences and improve stability of a H2O2 sensor, we designed a new hybrid material in which CNTs are covalently attached to a gold surface. First, a highly homogeneous nanostructured gold surface was formed on top of the SiO2 substrate with an intermediate layer of Ti, using E-beam evaporation technique. The average height of the gold nanostructures was 3.9 nm. The gold surface was then electrochemically grafted with aminophenyl groups. Further, plasma-functionalized densified CNT film made from CNT array was attached to the gold surface via amide formation reaction. An introduction of CNTs led to a 40-fold increase in current response. Formation of nanostructured gold surface without actual attachment of nanoparticles to the substrate, as well as covalent bonding of CNTs to the surface, provide a very high stability of the fabricated material, which, in turn, improves the repeatability of measurements.A designed electrode was used for non-enzymatic H2O2 detection. Under optimized parameters of square wave voltammetry and optimum pH, analysis of H2O2 can be performed using 5 independent oxidation peaks. The presence of multiple peaks is due to oxidation of gold, CNTs and H2O2 itself. All peaks increase when H2O2 is added in solution, because of chemical reduction of CNT and gold surfaces, and their consecutive electrochemical oxidation. Using the peak at -0.6 V allows for the H2O2 detection at very low potential, that can minimize interference from various reducing agents. For the -0.6 V peak, the limit of detection was 1.4 mM. Using the peak at -0.05 V allows for much higher sensitivity with the limit of detection of 500 nM.Almost no signal deterioration was observed after 200 measurements, proving high stability of the fabricated electrodes.

Nanocrystalline β-Ga2O3 thin film prepared by electron beam evaporation for enhanced photodetection

In this study, e-beam evaporation technique was used to fabricate thin-film (TF) of β-Ga2O3 on Si-substrate. The average crystallite size was determined to be roughly ∼39.8 nm. The deposition of β-Ga2O3 TF appears smooth and devoid of cracks or pits, with an average film thickness of ∼375 nm. From the ultraviolet (UV)–Vis absorption, the optical bandgap value for β-Ga2O3 TF was found to be about ∼4.84 eV. Our study found that the photodetector (PD) had excellent performance, characterized by an extremely low dark current of 4.02 × 10−8 A at −1 V bias, an I L/I D ratio over nine times, and the short rise and fall times of .27 s and .059 s. The simultaneous achievement of minimal dark current and quick rise and fall times is remarkable. The β-Ga2O3 TF PD’s remarkable consistency and reproducibility suggest promising practical applications for UV PDs.

Amorphous-crystalline phase transformation induced changes in linear and non-linear optical properties of Te/As2Se3 bilayer thin films

The current work describes the amorphous state to crystalline state transition upon diffusion of the top Te layer into the bottom As2Se3 layer at 200 °C annealing temperature. The Te/As2Se3 bilayer thin films were prepared by electron beam (e-beam) evaporation technique. The XRD study confirms the amorphous to crystalline phase transformation. The UV–Visible spectroscopy data shows significant changes in both linear and non-linear optical properties due to the diffusion of Te into As2Se3 upon thermal annealing. The phase transformation behaviour of the Te/As2Se3 bilayer thin films can be utilized in various optoelectronic applications.

Fabrication and characterization of nichrome metal based Schottky diode on silicon

Modern electronic devices are inconvincible without implementation of metal–semiconductor (M−S) junctions. Those junctions, either in Schottky or in Ohmic form, have been largely utilized in various energy, microelectronic mechanical systems (MEMS), and microelectronic devices. Present work demonstrates the fabrication and characterization of nichrome metal based Schottky diode on silicon. Nichrome metal has non-corrosive and antioxidant nature, which is vital for devices performing in hazardous environments. Under a vacuum of ∼ 10−6 torr, Nichrome metal (80% Nickle + 20% chromium) was deposited on an n-Si wafer with the e-beam evaporation technique. A shadow mask was used to delineate Schottky contact of diameter 0.5 mm. The manufactured device’s current–voltage characteristics were measured on room temperature and dominant current conduction mechanism, barrier height, ideality factor, were also identified. The non-ideality present in the device has been discussed in terms of defects at the interface.

Design and development of Fabry–Perot etalon based color filter using ebeam GLAD technique: Simulation and experiment

The design of Spatial Variable Color Filter (SVCF), based on the principle of Fabry–Perot (FP) etalon, has been analyzed in detail considering Ag as reflecting metallic layer and TiO2 as cavity layer. The effect of different thickness ranges of cavity layer for different order of interference peaks and the effect of varying thickness of reflecting layer has been investigated through simulation. A SVCF has been designed in the broad visible wavelength range of 464 to 670 nm based on the 2nd order interference peak of FP etalon for optimized spectral performance and it has been experimentally demonstrated using ebeam evaporation technique. The reflecting Ag layer has been deposited at normal angle and the tapered cavity layer of TiO2 has been deposited at 86° glancing angle. The distribution of thickness and dispersion relationship at various locations of the glancing angle deposited (GLAD) TiO2 thin films has been analyzed by spectroscopic ellipsometry measurements. The effect of lateral variation of dispersion properties of cavity layer caused by GLAD, on the spectral performance of the developed SVCF, has been investigated by both simulation and through spectral transmittance measurement. Overall results demonstrate the potential of the axial glancing angle deposition technique for the first time for development of SVCF in visible wavelength with high peak transmittance (∼67%) and a peak wavelength tunability of ∼4 nm/mm.

Designing mixed-metal electrocatalyst systems for photoelectrochemical dinitrogen activation.

Efficient artificial photosynthesis systems are currently realized as catalyst- and surface-functionalized photovoltaic tandem-and triple-junction devices, enabling photoelectrochemical (PEC) water oxidation while simultaneously recycling CO2 and generating hydrogen as a solar fuel for storable renewable energy. Although PEC systems also bear advantages for the activation of dinitrogen - such as a high system tunability with respect to the electrocatalyst integration and a directly controllable electron flux to the anchoring catalyst through the adjustability of incoming irradiation - only a few PEC devices have been developed and investigated for this purpose. We have developed a series of photoelectrodeposition procedures to deposit mixed-metal electrocatalyst nanostructures directly on the semiconductor surface for light-assisted dinitrogen activation. These electrocatalyst compositions containing Co, Mo and Ru in different atomic ratios follow previously made recommendations of metal compositions for dinitrogen reduction and exhibit different physical properties. XPS studies of the photoelectrode surfaces reveal that our electrocatalyst films are to a large degree nitrogen-free after their fabrication, which is generally difficult to achieve with traditional magnetron sputtering or e-beam evaporation techniques. Initial chronoamperometric measurements of the p-InP photoelectrode coated with the Co-Mo alloy electrocatalyst show higher photocurrent densities in the presence of N2(g) than in the presence of Ar at -0.09 V vs. RHE. Indications of successful dinitrogen activation have also been found in consecutive XPS studies, where both N 1s and Mo 3d spectra reveal evidence of nitrogen-metal interactions.

Comparison of Sputtered and Evaporated Vanadium Pentoxide Thin Films for Resistive Microbolometer Application

V2O5 thin films have made impressive progress in the development of resistive microbolometers. The challenging parameters for microbolometers are the active material selection and the deposition methods. It might be a more promising way to achieve a good performance of the devices. The present work deals with the V2O5 thin films fabricated on soda lime glass substrates by using e-beam evaporation and magnetron sputtering techniques at a substrate temperature of 200 °C. Afterward, samples were annealed at 300 and 400 °C for 1 h to obtain uniform and stoichiometric thin films. X-ray Diffraction (XRD) showed that the thin films deposited by magnetron sputtering were amorphous in nature, even after annealing at elevated temperatures; however, the thin films fabricated by the electron beam evaporation technique show crystalline nature, which was improved by annealing. XRD also revealed various mixed phases of VOx in electron beam-deposited films. Optical properties were determined using UV-Visible spectroscopy, which showed a decrease in transmittance from 81% down to 57% by increasing the annealing temperature. Similarly, the band gap calculated for electron beam evaporated and magnetron sputtered V2O5 thin films was observed in the range of 1.41 to 2.25 eV. Rutherford backscattering (RBS) was performed to determine the thickness and composition of the films. Slight variations have been observed in intended and deposited thicknesses of films fabricated by e-beam and sputtering techniques. Structural properties revealed by Field Emission Scanning Electron Microscope (FESEM) were found to be the uniform, compact and dense surface of the as-deposited and 300 °C annealed samples. However, annealing at 400 °C changed the surface morphology into nanorods in e-beam and plate-like structures in the sputtered film. EDS proved the elemental concentration of vanadium and oxygen in these V2O5 thin films. Electrical properties were investigated using the Hall measurement technique which showed better conductivity of sputtered films than e-beam deposited films. It can be concluded that the cost-effective and reliable microbolometers infrared (IR) sensors can be fabricated using annealed sputtered films.

Structural, optical, and electrical properties of e-beam deposited metamaterials of granular CdSe thin films on glass substrates with a thin buffer layer of HfO2 dielectric

Structural, optical, and electrical properties of granular thin films of CdSe deposited on HfO2 dielectric layer are reported. The thin films were deposited on fluorine-doped tin oxide (FTO) coated glass substrates by e-beam evaporation technique. Structural analysis revealed the amorphous nature of the HfO2, whereas wurtzite type hexagonal crystal structure was observed in the CdSe thin films. Microstructural analysis showed the granular nature of both the deposited layers. The optical and electrical properties of the thin films were studied in detail. The dielectric properties of the deposited layers were studied in correlation with their microstructure. The appearance of negative permittivity (NP) in the films indicates towards metamaterial type characteristics which has various potential applications viz. high permittivity capacitors, microwave filters, coil free resonators, and thin film transistors (TFTs).

In-situ evolution of temperature dependent attenuation coefficients of plasmonic silver nanostructures

With a growing interest in high temperature applications of plasmonic metal nanostructures, the morphological modulation and the evolution of optical constants of these plasmonic nanostructures have become important both from fundamental growth dynamics point of view and from optical applications viewpoint. In the present investigation, set of plasmonic silver nanostructures (thickness range 5–25 nm) have been grown by e-beam evaporation technique with varying deposition time. They have been subjected to temperature dependent in-situ spectroscopic ellipsometry measurements for optical analysis at room temperatures (25 °C) and at various elevated temperatures (80 °C–530 °C). The evolutions of optical and surface morphological parameters of these Ag nanostructures as a function of thicknesses have also been investigated. The optical attenuation coefficients (400–700 nm) of these Ag nanostructures are found to evolve in a different fashion depending upon thickness controlled nano-morphology. For low thickness films (5–16 nm), which consists of discrete Ag grains, the light attenuation coefficient initially decreases up to ∼130 °C and subsequently increases with increasing temperature up to 300 °C. This is due to the competition of two counteracting phenomena of reduction of electron-grain boundary scattering and increase in LSPR absorption effect due to temperature induced grain expansion. In contrast, for the relatively thicker films (>16 nm), the optical attenuation coefficient was found to decrease with increasing temperature due to dominance of former effect over later which is caused by larger grain size and network-like nano-morphology. The investigated temperature dependent evolution of optical properties is relevant in studies of physical processes at elevated temperatures and also for accurate modeling of plasmonic devices in high-temperature applications.

PbS and PbO Thin Films via E-Beam Evaporation: Morphology, Structure, and Electrical Properties.

Thin films of lead sulfide (PbS) are being extensively used for the fabrication of optoelectronic devices for commercial and military applications. In the present work, PbS films were fabricated onto a soda lime glass substrate by using an electron beam (e-beam) evaporation technique at a substrate temperature of 300 °C. Samples were annealed in an open atmosphere at a temperature range of 200–450 °C for 2 h. The deposited films were characterized for structural, optical, and electrical properties. Structural properties of PbS have been studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and Rutherford backscattering spectrometry (RBS). The results of XRD showed that the PbS thin film was crystalline in nature at room temperature with cubic crystal structure (galena) and preferential (111) and orientation (022). The morphology of the thin films was studied by FESEM, which also showed uniform and continuous deposition without any peel-off and patches. EDS analysis was performed to confirm the presence of lead and sulfur in as-deposited and annealed films. The thickness of the PbS film was found to be 172 nm, which is slightly greater than the intended thickness of 150 nm, determined by RBS. Ultraviolet-Visible-Near-Infrared (UV-Vis-NIR) spectroscopy revealed the maximum transmittance of ~25% for as-deposited films, with an increase of 74% in annealed films. The band gap of PbS was found in the range of 2.12–2.78 eV for as-deposited and annealed films. Hall measurement confirmed the carriers are p-type in nature. Carrier concentration, mobility of the carriers, conductivity, and sheet resistance are directly determined by Hall-effect measurement. The as-deposited sample showed a conductivity of 5.45 × 10−4 S/m, which gradually reduced to 1.21 × 10−5 S/m due to the composite nature of films (lead sulfide along with lead oxide). Furthermore, the present work also reflects the control of properties by controlling the amount of PbO present in the PbS films which are suitable for various applications (such as IR sensors).

Comparative study of titanium, platinum, and titanium nitride thin films for micro-elecrto mechanical systems (MEMS) based micro-heaters

This paper presents a comparative study of titanium (Ti), platinum (Pt), and titanium nitride (TiN) micro-electro mechanical systems based micro-heaters. In the present study, a common geometry and thin film thicknesses were selected to achieve comparable base resistances for all three microheater materials. Titanium, platinum, and titanium nitride thin films are deposited using DC magnetron sputtering, E-beam evaporation, and reactive DC magnetron sputtering techniques, respectively, and deposited thicknesses were verified using scanning electron microscopy. Mechanical properties such as Young’s modulus and hardness were also evaluated using nano-indentation. Later, the micro-heaters were fabricated, packaged, and characterized. The thermal coefficient of resistance (TCR) was found to be 4146, 2641, and 487 ppm/°C for Ti, Pt, and TiN micro-heaters, respectively. Power–temperature (P–T) characterization showed that the power required to reach the set temperature is comparable for all the above micro-heater materials. The TiN micro-heater exhibits a linear voltage–current (V–I) characteristic compared to platinum and titanium micro-heaters. The temperatures measured using infra-red imaging were comparable to those calculated by TCR measurements. Furthermore, thermal stability studies have been performed on all micro-heaters for 110 h. TiN microheaters were found to be more stable and resilient to external environmental conditions than Ti and Pt microheaters because of their lower TCR values.

Synergistic interactions between water and the metal/oxide interface in CO oxidation on Pt/CeO2 model catalysts

The significance of catalytic active interfacial sites in metal supported on metal oxide systems has been well established in prototypical CO oxidation reactions. Here, we investigate the role of water molecules in the CO oxidation reaction using Pt nanoparticles (Pt NPs) supported by a two-dimensional (2D) cerium oxide thin-film. The 2D model CeO2 thin films were fabricated using the e-beam evaporation technique and a monolayer of Pt nanoparticles deposited on CeO2 thin films by the Langmuir-Blodgett (LB) method. The well-defined reaction conditions, such as humid and dry conditions, were achieved using an ultra-high vacuum (UHV) batch chamber. Interestingly, we found a strong metal-support interaction (SMSI) in the Pt/CeO2 catalyst under dry reaction conditions, which was increased further by the presence of water molecules. However, water had a detrimental effect on a Pt thin-film model catalyst under humid reaction conditions. By altering the partial pressures of water molecules and CO, the reaction mechanism was established under humid conditions. The current results demonstrate that hydroxyl intermediates from water molecules provide an alternative pathway to the Pt/CeO2 catalyst, resulting in increased overall turnover rates. These findings shed light on the synergistic interplay of water and metal-oxide interfaces.

Synthesis and Characterization of Nanostructured Multi-Layer Cr/SnO2/NiO/Cr Coatings Prepared via E-Beam Evaporation Technique for Metal-Insulator-Insulator-Metal Diodes.

Enhanced non-linearity and asymmetric behavior of the Cr/metal oxide diode is reported, with the addition of two insulator layers of SnO2 and NiO to form the metal-insulator-insulator-metal (MIIM) configuration. Such an MIIM diode shows potential for various applications (rectifiers and electronic equipment) which enable the femtosecond fast intoxication in MIIM diodes. In this work, nanostructured multi-layer Cr/SnO2/NiO/Cr coatings were fabricated via e-beam evaporation with the following thicknesses: 150 nm/20 nm/10 nm/150 nm. Coatings were characterized via Rutherford backscattering (RBS), scanning electron microscopy (SEM), and two-probe conductivity testing. RBS confirmed the layered structure and optimal stoichiometry of the coatings. A non-linear and asymmetric behavior at <1.5 V applied bias with the non-linearity maximum of 2.6 V−1 and the maximum sensitivity of 9.0 V−1 at the DC bias point was observed. The promising performance of the coating is due to two insulating layers which enables resonant tunneling and/or step-tunneling. Based on the properties, the present multi-layer coatings can be employed for MIIM application.

Design and fabrication of self-compensating ZnSe beam splitter in LWIR region

The design and fabrication of a self-compensating beam splitter in the Long-wave infrared (LWIR) wavelength range is discussed in the article. The self-compensating plate beam splitter finds its application in a passive Fourier Transform Infrared (FTIR) system for the detection of chemical warfare clouds from a distance of up to a few kilometers. The beam splitter was designed for the LWIR wavelength band of 8.0–12.0 µm, with a beam splitting ratio of 50:50, i.e., for 50% transmission and 50% reflection @ 45° angle of incidence (AOI). The zinc selenide (ZnSe) based beam splitter was developed using an ion-assisted e-beam evaporation technique. A Perkin Elmer FTIR spectrometer was used to measure the average transmission/reflection of 50:50 in the 8.0–12.0 µm wavelength band. The fabricated beam splitter complied with MIL-F-48616 environmental tests with no visible damage to the coated optics. The fabricated ZnSe self-compensating beam splitter was integrated in the Michelson interferometer set-up and the interferogram is recorded.