Ion Mass Spectrometry Depth Profiling Research Articles

Formation of Wrinkle Structures on Styrene-b-isoprene-b-styrene Films Using One-Step Ion-Beam Irradiation

We investigated the wrinkle formation on ion-beam (IB)-irradiated substrates coated with the thermoplastic elastomer styrene-b-isoprene-b-styrene (SIS) and demonstrate a relation of the wrinkle structure and the newly formed top layer induced by IB. IB irradiation led to polymer crosslinking on the surface, thereby forming a new skin layer, a finding which was supported by an X-ray photoelectron spectroscopy analysis, Young's moduli calculated using force-distance curves, and time-of-flight secondary ion mass spectrometry depth profiling. The wrinkle wavelength increased according to the irradiation time, which indicates that the latter mainly increased the thickness of the crosslinking layer. The increase in the wrinkle wavelength varied from 420 to 670 nm by changing the IB irradiation time. In this paper, we present not only the expectation of wrinkle fabrication using our method, but also the possibility of choosing diverse materials such as the thermoplastic elastomer SIS for fabrication of wrinkle structures.

Oxygen diffusion in oxide thin films grown on SrTiO3

$\mathrm{SrTi}{\mathrm{O}}_{3}$ thin films were grown on $^{18}\mathrm{O}$-exchanged $\mathrm{SrTi}{\mathrm{O}}_{3}$ single crystalline substrates by pulsed-laser deposition, rf sputtering, and oxide molecular-beam epitaxy to study their oxygen diffusion depth profiles using secondary ion mass spectrometry and elastic recoil detection analysis depth profiling. The oxygen depth profiling shows that $\mathrm{SrTi}{\mathrm{O}}_{3}$ films prepared with the three different deposition techniques will take oxygen from the substrate, even at room temperature. This confirms that the substrate is one possible oxygen source for the growth of oxide thin films independent of the physical vapor deposition technique employed. It was also found that a reactive oxygen environment changes the oxygen composition of the substrate during the growth of a film and partly replaces $^{18}\mathrm{O}$ with $^{16}\mathrm{O}$ up to a depth of several tens of nm. These findings imply that $\mathrm{SrTi}{\mathrm{O}}_{3}$ and therefore other ion conducting oxide substrates, which are commonly used as platforms for thin film growth, can be considered capricious in nature with respect to oxygen chemistry and lattice constants.

Synthesis of MnSb2O6 powders through a simple low-temperature method and their test as a gas sensor

In this work, a simple and economical chemical method was used to synthesize MnSb2O6 nanoparticles for their potential application as a gas sensor. The nanoparticles of the oxide were analyzed by powder X-ray diffraction, finding the crystalline phase at 600 °C. The crystallized oxide presented a hexagonal crystalline structure with spatial group P321. The microstructure of the material was analyzed by field-emission scanning electron microscopy, finding surface morphologies such as micro-plates, microspheres (diameter ~ 0.69 μm), and other particles without apparent shape. The average size of the nanoparticles was estimated at ~ 32.0 nm, according to images obtained by transmission electron microscopy (TEM). Oxidation states of the atomic elements forming the MnSb2O6 nanoparticles were found by X-ray photoelectron spectroscopy measurements. In the case of Mn, two oxidation states Mn2+ and Mn3+ corresponding to the Mn 2p3/2 state were observed at 641.26 and 642.7 eV, respectively. For Sb, the Sb3+ oxidation state, associated with the Sb 3d3/2 state, was located at 539.82 eV. The peak assigned to O at 530.82 eV overlaps the Sb 3d5/2. The secondary ion mass spectrometry depth profiling showed a good distribution of the atomic elements in the nanoparticles, without additional elements or impurities. The optical properties were also studied by photoacoustic spectroscopy, revealing a direct transition of the MnSb2O6 nanoparticles with a band gap energy of 1.78 eV. The gas detection tests were performed in C3H8 and CO atmospheres at different concentrations and operating temperatures. The oxide showed an interesting behavior as the concentrations of the testing gases and the operating temperature increased. The high response presented by the MnSb2O6 suggests that this material can be used as a gas sensor.

Solid-State Carbon-Doped GaN Schottky Diodes by Controlling Dissociation of the Graphene Interlayer with a Sputtered AlN Capping Layer.

Carbon-doped GaN (GaN:C) Schottky diodes are prepared by controlling the destruction status of the graphene interlayer (GI) on the substrate. The GI without a sputtered AlN capping layer (CL) was destroyed because of ammonia precursor etching behavior in a high-temperature epitaxy. The damaged GI, like nanographite as a solid-state carbon doping source, incorporated the epitaxial growth of the GaN layer. The secondary ion mass spectroscopy depth profile indicated that the carbon content in the GaN layer can be tuned further by optimizing the sputtering temperature of AlN CL because of the better capping ability of high crystalline quality AlN CL on GI being achieved at higher temperature. The edge-type threading dislocation density and carbon concentration of the GaN:C layer with an embedded 550 °C-grown AlN CL on a GI substrate can be significantly reduced to 2.28 × 109 cm-2 and ∼2.88 × 1018 cm-3, respectively. Thus, a Ni-based Schottky diode with an ideality factor of 1.5 and a barrier height of 0.72 eV was realized on GaN:C. The series resistance increased from 28 kΩ at 303 K to 113 kΩ at 473 K, while the positive temperature coefficient (PTC) of series resistance was ascribed to the carbon doping that induced the compensation effect and lattice scattering effect. The decrease of the donor concentration was confirmed by temperature-dependent capacitance-voltage (C-V-T) measurement. The PTC characteristic of GaN:C Schottky diodes created by dissociating the GI as a carbon doping source should allow for the future use of high-voltage Schottky diodes in parallel, especially in high-temperature environments.

Effect of background atmosphere and substrate temperature on SrO:Bi3+(0.2 mol%) thin films produced using pulsed laser deposition with different lasers

SrO:Bi3+ (0.2 mol%) phosphor thin films were grown by pulsed laser deposition (PLD) on Si (100) substrates in vacuum and different O2 atmospheres at different substrate temperatures using a Nd:YAG laser (266 nm) with energy 33.3 mJ/pulse, a KrF laser (248 nm) with energy 300 mJ/pulse or a ArF laser (193 nm) with energy 150 mJ/pulse. The microstructure and photoluminescence (PL) of these films were found to be highly dependent on the background atmosphere and substrate temperature. X-ray diffraction (XRD) analysis showed that the SrO:Bi3+ (0.2 mol%) films varied from amorphous to highly crystalline depending on the deposition conditions. Atomic Force Microscope results showed that the surface roughness decreased as the substrate temperature increased. The main PL emission peak position of the thin films showed a shift to shorter wavelengths at 427 nm, when compared to the powder (445 nm). The difference in wavelength was attributed to the Bi3+ ions, which are very sensitive towards the environment. Time of flight secondary ion mass spectroscopy depth profiles for the samples deposited in vacuum and O2 at different substrate temperatures look similar, except for a slight thickness variation.

Diffusion of calcium in forsterite and ultra-high resolution of experimental diffusion profiles in minerals using local electrode atom probe tomography

We report measurements of experimentally induced diffusion profiles in minerals using local electrode atom probe (LEAP) tomography, and demonstrate that this is a viable technique for use in experimental diffusion studies, with distinct advantages over current state-of-the-art techniques such as secondary ion mass spectrometry and Rutherford backscattering spectroscopy. For this purpose, we have investigated Ca diffusivity in synthetic forsterite, which we measured parallel to [1 0 0] from 750 to 1300 °C, at 1 atm. pressure in air, with silica activity buffered by forsterite-enstatite or forsterite-periclase assemblages. We observe no dependence of Ca diffusion on silica activity, and argue that this may be due the strong preference of Ca for the M2 site, while M-site vacancies in olivine are more favorably located in M1 sites. Taken together, our data yield the following Arrhenius relation for Ca diffusion parallel to [1 0 0] in synthetic forsterite at 1 atm. pressure: logDCa_[100]m2s-1=-8.42±0.36-250±9kJmol-12.303RT. Time series experiments at 750 °C reveal that the shortest profiles measured by secondary ion mass spectrometry depth profiling (using an oxygen primary ion beam) are compromised by ion-beam mixing, while LEAP tomography yields accurate diffusion coefficients from the same samples. Because LEAP tomography does not suffer from the type of analytical artefacts that complicate the measurement of extremely short profiles via secondary ion mass spectrometry depth profiling, and also typically produces an order of magnitude better sensitivity than Rutherford backscattering spectroscopy, this technique offers a valuable new tool for quantifying the diffusivities of slow-diffusing trace elements in crystalline materials.

Investigating SEI Formation Methods on the Graphite Anode Interface Using Nuclear Reaction Analysis

Observing and managing the functional characteristics of solid electrolyte interphases (SEIs) has been a central topic in lithium-ion battery research for many years. Recently, Antonopoulos et al. reported that forming SEIs on composite graphite electrodes in a high-potential region (1.2 - 0.78 V vs. Li/Li+) has a significant influence on rate capability in half cell formats. [1] In our work, we reviewed several formation methods in full cell devices and studied their impact on the SEI via Li nuclear reaction analysis (Li-NRA) measurements on post-mortem electrodes. This novel technique was previously used to study Li-ion electrode interfaces by Schultz et al. (2017). By detecting gamma emissions from the reaction [7Li (p,γ)8Be] between incident hydrogen ions of specific energies and Li in the sample, we obtained a qualified Li content profile. The NRA results were compared with secondary ion mass spectrometry (SIMS) depth profiles and X-ray photoelectron spectra (XPS). These profiles showed relatively high levels of lithium in the surface region of the anode (~150 nm deep) with variation among electrodes using different formation procedures. This finding, connected with a reduced rate capability for some cells, implies that the buildup of Li at the anode interface may be an important factor influencing the full cell performance after formation.

LATP and LiCoPO4 thin film preparation – Illustrating interfacial issues on the way to all-phosphate SSBs

Thin film solid-state batteries are suitable model systems for the study of degradation phenomena in bulk solid-state batteries. As a necessary prerequisite for the construction of thin film batteries, high quality thin films of electrode materials and solid electrolytes have to be deposited. In this study, phosphate-based cathode (LiCoPO4) and solid electrolyte (Li1.5Al0.5Ti1.5(PO4)3) thin films were successfully deposited by pulsed laser deposition on silicon substrates. By temperature dependent grazing incidence X-ray diffraction measurements, the high quality of the deposited thin films was shown as well as crystallization temperatures were determined. Moreover, atomic force microscopy and scanning electron microscopy measurements were carried out for surface analysis, highlighting the surface smoothness of the films and unraveling the microstructure of the deposited LATP films, which contain grain boundaries. Further, a model interface composed of a thin layer of LiCoPO4 of varying thickness on top of Li1.5Al0.5Ti1.5(PO4)3 was used to corroborate information about changes in the chemical state of the materials as well as to track the inter-diffusion across the interface of all corresponding ionic species. This was done by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry depth profiling. While well-defined interfaces were observed for unheated interfaces, significant inter-diffusion of transition metal ions was observed between heated LATP and LCP films. Despite inter-diffusion, no changes in the chemical states were observed at the interface, excluding significant phase transformations to compounds with altered oxidation states. Although stable phosphate-based materials were chosen for, both, electrolyte and active material to diminish known instabilities of the interface in this study, the need for interfacial layers arises to suppress the inter-diffusion, which may affect lithium ion transport across the interface. This work provides detailed insight into the complex problems of interfacial stability in all-solid-state batteries.

Epitaxial n++-InGaAs ultra-shallow junctions for highly scaled n-MOS devices

High electron mobility III-V semiconductors like InGaAs are excellent candidates for sub-10 nm n-metal-oxide-semiconductor (nMOS) devices. One of the critical challenges in downscaling III-V devices is achieving low-resistance contacts by forming low-defect, ultra-shallow junctions <9 nm in depth, with n-type dopant concentrations above 1019 cm−3. In the current study, we combine time-of-flight secondary ion mass spectrometry (ToF-SIMS) depth profile analysis, atomic force microscopy (AFM) imaging, and high-resolution transmission electron microscopy (HR-TEM) to determine the optimal doping strategy for growing Si-doped n++-In0.25Ga0.75As ultra-shallow junctions by molecular beam epitaxy. We test three different approaches to doping: homogeneous co-deposition, single δ-layer (continuous) doping, and triple δ-layer (pulsed) doping. We demonstrate the formation of technologically suitable n++-In0.25Ga0.75As junctions 5–7 nm deep, grown under As-rich conditions with a single δ-layer at temperatures as low as 400 °C. These junctions have peak Si concentrations between 6 × 1019 and 1 × 1020 cm−3 and high crystal quality. The surface self-organizes into smooth ripples or mounds, up to a peak dopant concentration of ~2 × 1020 cm-3. Above this value, enhanced diffusion of Si and In due to a large population of Ga vacancies increases lattice strain in the semiconductor epilayer, triggering a transition from 2D growth to 3D growth and the formation of In0.85Ga0.15As clusters on the surface.

Optical Properties of MBE-Grown Hg1−xCdxSe

In this work, we present a study on the temperature-dependent infrared absorption spectra of Hg1−xCdxSe grown by molecular beam epitaxy (MBE) on GaSb (211) substrate, having a nominal x-value of 0.21. For temperatures below 200 K, the observed optical bandgap is found to correspond to the Fermi energy level rather than the intrinsic bandgap, which is quantitatively explained by the Burstein–Moss shift due to the presence of a background electron concentration of 3.5 × 1016 cm−3. In addition, empirical formulae for calculating both the absorption edge and intrinsic absorption coefficient in the Kane region have been derived from the previously reported absorption spectra of Bridgeman-grown Hg1−xCdxSe samples (0.15 ≤ x ≤ 0.3). By employing the empirical expressions, the infrared transmission spectra have been modeled based on the characteristic matrix method, and the x value profile of the sample along the growth direction has been determined, which is in good agreement with the experimental results obtained from secondary ion mass spectrometry (SIMS) depth profiling combined with Rutherford backscattering spectrometry (RBS).

Enhanced p-Type Doping in Polycrystalline CdTe Films: Deposition and Activation

An in situ nonequilibrium method to increase hole density in polycrystalline CdTe thin films to 1016 cm−3 using group V substitution on Te is presented. Single-phase CdTe films doped with P, As, and Sb were deposited at 550 °C at 100–200 nm/s onto moving cadmium sulfide/high resistance transparent buffer layer/transparent conductive oxide /glass superstrates by vapor transport deposition in Cd overpressure from high purity compound sources. Doping levels before and after activation were determined by capacitance-voltage analysis of diagnostic devices. Secondary ion mass spectrometry depth profiling confirmed dopant incorporation levels of 1017–1018 atoms/cm3 in as-deposited films. Electronic activation was carried out by post-deposition annealing in Cd or CdCl2 vapor with fast cooling, increasing acceptor concentrations to >1015 cm−3 for P and >1016 cm−3 for As and Sb, compared with mid −1014 cm−3 acceptor levels for undoped CdTe films. The activation methods are compatible with post-deposition processing presently used for high-efficiency CdTe solar cells. For the dopants As and Sb, the acceptor concentration increased by substitutional AsTe and SbTe formation, respectively, which was validated by cathodoluminescence spectroscopy.

Investigation of strontium transport and strontium quantification in cortical rat bone by time-of-flight secondary ion mass spectrometry.

Next-generation bone implants will be functionalized with drugs for stimulating bone growth. Modelling of drug release by such functionalized biomaterials and drug dispersion into bone can be used as predicting tool for biomaterials testing in future. Therefore, the determination of experimental parameters to describe and simulate drug release in bone is essential. Here, we focus on Sr2+ transport and quantification in cortical rat bone. Sr2+ dose-dependently stimulates bone-building osteoblasts and inhibits bone-resorbing osteoclasts. It should be preferentially applied in the case of bone fracture in the context of osteoporotic bone status. Transport properties of cortical rat bone were investigated by dipping experiments of bone sections in aqueous Sr2+ solution followed by time-of-flight secondary ion mass spectrometry (ToF-SIMS) depth profiling. Data evaluation was carried out by fitting a suitable mathematical diffusion equation to the experimental data. An average diffusion coefficient of D = (1.68 ± 0.57) · 10-13 cm2 s-1 for healthy cortical bone was obtained. This value differed only slightly from the value of D = (4.30 ± 1.43) · 10-13 cm2 s-1 for osteoporotic cortical bone. Transmission electron microscopy investigations revealed a comparable nano- and ultrastructure for both types of bone status. Additionally, Sr2+-enriched mineralized collagen standards were prepared for ToF-SIMS quantification of Sr2+ content. The obtained calibration curve was used for Sr2+ quantification in cortical and trabecular bone in real bone sections. The results allow important insights regarding the Sr2+ transport properties in healthy and osteoporotic bone and can ultimately be used to perform a simulation of drug release and mobility in bone.

Effect of substrate off-orientation on the characteristics of GaInP/AlGaInP single heterojunction solar cells

The effects of GaAs substrate off-orientation on GaInP/AlGaInP heterojunction solar cells were investigated. The performances of solar cells fabricated on 2° and 10° off GaAs substrates were compared. The short circuit current densities were 10.44 mA/cm2 for the 10° off sample, 7.15 mA/cm2 and 7.41 mA/cm2 for the 2° off samples, which showed 30% higher short-circuit current density for 10° off samples. Also, 30% higher external quantum efficiencies and smooth surface morphology were observed in the solar cell fabricated on the 10° off GaAs substrate. Secondary ion mass spectrometry depth profiles showed that the solar cells on 2° off substrates had a 20-times higher oxygen concentration than the solar cells on 10° off GaAs substrate in the n-GaAs/GaAs buffer layer. The 30% reduction for the solar cells on 2° substrates in short circuit current density (Jsc) was attributed to the higher oxygen concentration of the 2° off samples than the 10° off samples. I-V characteristics comparison between different front contact grid patterns was also performed for optimization of grid contacts. A 0.47 V bandgap-voltage offset, one of the device performance figures of merit to compare PV cells with different materials, was obtained.

Probing a chemical state during ultra low impact energy secondary ion mass spectrometry depth profiling

Ultra low impact energy SIMS allows probing a chemical state and provides qualitative information about strong covalent bonds.

Effect of annealing temperature on the interfacial interaction of LiNi0.5Mn1.5O4 thin film cathode with stainless-steel substrate

LiNi0.5Mn1.5O4 thin films were coated on stainless steel substrates by radio-frequency sputtering at room temperature for a lithium-ion battery. The cathode films were post-annealed at 500, 600 and 700 °C to study (i) the impact of annealing temperature on the crystallization of the cathode film and (ii) the reactivity between the cathode film and the stainless steel substrate. X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy were adopted to characterize the thin films. The electrochemical properties of the LiNi0.5Mn1.5O4 cathodes were investigated with cyclic voltammetry and galvanostatic charge/discharge tests. As the annealing temperature increased from 500 to 600 °C, the crystallinity and electrochemical characteristics of LiNi0.5Mn1.5O4 both improved. However, as the annealing temperature further increased to 700 °C, the phase purity and the electrochemical performance were greatly deteriorated. Combined chemical analyses with time-of-flight secondary ion mass spectrometry depth profiling and energy-dispersive X-ray spectroscopy in scanning transmission electron microscopy mapping have indicated that the cross-diffusion of metal ions between LiNi0.5Mn1.5O4 and the stainless steel substrate takes place at a temperature higher than 600 °C, which was attributed as a main origin of the phase change in the LiNi0.5Mn1.5O4 cathode layer and electrochemistry degradations of lithium-ion battery.

A quantitative evaluation of inorganic boundary films formed in engine oils by TOF‐SIMS depth profiling with low energy Cs sputtering

Quantitative evaluation of lubrication boundary films was investigated by time‐of‐flight secondary ion mass spectrometry depth profiling with low energy Cs sputtering. Relative sensitivity correction coefficient (RSC) for calcium phosphate, calcium carbonate, or calcium sulfate was determined by measuring the pellets of the mixture of these compounds. The RSCs for the three calcium salts varied with measurement conditions such as sputter energy and primary ion species. By using the RSC determined in this investigation, the depth profiles of the boundary films formed in real engine oil were corrected to quantitative profiles. The difference of structures between two lubrication boundary films on the different substrate materials formed in the same engine oil was clarified.

Evaluation of sputtering induced surface roughness development of Ni/Cu multilayers thin films by Time-of-Flight Secondary Ion Mass Spectrometry depth profiling with different energies O2+ ion bombardment

As a follow up on a previous paper on the quantitative evaluation of sputtering induced surface roughness and its influence on Auger electron spectroscopy depth profiling of polycrystalline Ni/Cu multilayers thin films, the ion sputtering induced surface roughness of these multilayered Ni/Cu polycrystalline thin films under low energy (0.5, 1.0 and 2.0 keV) O2+ ion bombardment and 1.0 keV Cs+ ion sputtering were investigated with Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and Atomic Force Microscopy (AFM). The lowest energy (0.5 keV) O2+ ion sputtering gave the best depth resolution for the different energy ion sputtering. Furthermore the 1.0 keV Cs+ ion sputtering led to a better resolution than the O2+ ion sputtering. The ToF-SIMS depth resolution was also better than the AES depth profiling with a 2.0 keV Ar+ ion sputtering. The Mixing-Roughness-Information depth (MRI) model used for fitting of the ToF-SIMS depth profiles accounts for the broadening upon experimental depth profiling owing to the effects of atomic mixing, surface roughness and information depth. The MRI fitted roughness parameters obtained from the ToF-SIMS depth profiling are in good agreement with the root-mean-square roughness obtained from the AFM topography scans of the crater bottom. Ion sputtering induced roughness and depth resolution during ToF-SIMS depth profiling of Ni/Cu multilayers were quantitatively evaluated according to the MRI fitting parameters.

A-Crater-within-a-Crater Approach for Secondary Ion Mass Spectrometry Evaluation of the Quality of Interfaces of Multilayer Devices.

Further development and optimization of modern optoelectronic devices requires fast and reliable procedures that may evaluate the quality of interfaces. For thick multilayer devices, mixing effect may significantly prevent proper interpretation of secondary ion mass spectrometry depth profiles especially if a region of interest is located far from the sample surface. In this work, we present how to overcome this problem with a so-called a-crater-within-a-crater approach. In this notion, a high energetic primary ion beam is used to rapidly remove most of the material forming a large crater. Then, the energy is significantly reduced and a new smaller crater is formed at the bottom of the previous one. Close to the region of interest, the impact energy is decreased to 150 eV and thus an interface can be analyzed with minimal mixing effect and thus its quality can be adequately assessed. Usefulness of this approach is tested on an epitaxial structure of a triple-junction solar cell and reliable information about the structure imperfection has been obtained: p and n dopants in the tunnel junction overlapped, deteriorating the operation of the device.

Secondary ion mass spectrometry depth profiling of ultrathick films using an argon gas cluster source: Crater shape implications on the analysis area as a function of depth

Argon cluster ions have enabled molecular depth profiling to unprecedented depths, with minimal loss of chemical information or changes in sputter rate. However, depth profiling of ultrathick films (&gt;100 μm) using a commercial ion source oriented at 45° to the surface causes the crater bottom to shrink in size because of a combination of the crater wall angle, sputter rate differences along the trailing‐edge crater wall, and undercutting on the leading‐edge. The shrinking of the crater bottom has 2 immediate effects on dual‐beam depth profiling: first is that the centering of the analysis beam inside the sputter crater will no longer ensure the best quality depth profile because the location of the flat crater bottom progressively shifts toward the leading‐edge and second, the shifting of the crater bottom enforces a maximum thickness of the film that could be depth profiled. Experiments demonstrate that a time‐of‐flight secondary ion mass spectrometry instrument equipped with a 20 keV argon cluster source is limited to depth profiling a 180 μm‐thick film when a 500 μm sputter raster is used and a 100 μm square crater bottom is to be left for analysis. In addition, depth profiling of a multilayer film revealed that the depth resolution degrades on trailing‐edge side of the crater bottom presumably because of the redeposition of the sputtered flux from the crater wall onto the crater bottom.

Chemical Vapor Deposition Carbon Film as a Capping Layer in 4H-SiC Based MOSFETs.

Radio-frequency plasma enhanced CVD (RF-PECVD) carbon films were grown directly on 4-inch 4H-SiC substrates as a capping layer for MOSFET device applications. An approximately 50-nm-thick CVD carbon capping layer was found to reduce the surface roughness, as determined by atomic force microscopy (AFM). The secondary ion mass spectroscopy (SIMS) depth profile results revealed that carbon capping layer can suppress the dopant out-diffusion on the implanted surface after annealing even at high temperature (1700 °C) for 30 min. The calculated subthreshold swing (S) values of devices with CVD carbon capping layer and photo-resist process (base) measured at room temperature were 460 ± 50 (mV/dec) and 770 ± 70 (mV/dec), respectively. The lower value of 'S' for the device with carbon capping layer was related to the very low density of interface traps at the SiC-SiO2 interface. These results show the potential of CVD carbon as a capping layer for SiC MOSFET device applications.