Nitrogen investigation by SIMS in two wide band-gap semiconductors: Diamond and Silicon Carbide

International audienceDiamond and Silicon Carbide (SiC) are promising wide band-gap semiconductors for power electronics, SiC being more mature especially in term of large wafer size (that has reached 200 mm quite recently). Nitrogen impurities are often used in both materials for different purpose: increase the diamond growth rate or induce n-type conductivity in SiC. The determination of the nitrogen content by secondary ion mass spectrometry (SIMS) is a difficult task mainly because nitrogen is an atmospheric element for which direct monitoring of N ions give no or a weak signal. With our standard diamond SIMS conditions, we investigate 12C14N-secondary ions under cesium primary ions by applying high mass resolution settings. Nitrogen depthprofiling of diamond and SiC (multi-) layers is then possible over several micrometer thick over reasonable time analysis duration. In a simple way and without notably modifying our usual analysis process, we found a nitrogen detection limit of 2x10 17 at/cm 3 in diamond and 5x10 15 at/cm 3 in SiC

Nitrogen investigation by SIMS in two wide band-gap semiconductors: Diamond and Silicon Carbide

International audienceDiamond and Silicon Carbide (SiC) are promising wide band-gap semiconductors for power electronics, SiC being more mature especially in term of large wafer size (that has reached 200 mm quite recently). Nitrogen impurities are often used in both materials for different purpose: increase the diamond growth rate or induce n-type conductivity in SiC. The determination of the nitrogen content by secondary ion mass spectrometry (SIMS) is a difficult task mainly because nitrogen is an atmospheric element for which direct monitoring of N ions give no or a weak signal. With our standard diamond SIMS conditions, we investigate 12C14N-secondary ions under cesium primary ions by applying high mass resolution settings. Nitrogen depthprofiling of diamond and SiC (multi-) layers is then possible over several micrometer thick over reasonable time analysis duration. In a simple way and without notably modifying our usual analysis process, we found a nitrogen detection limit of 2x10 17 at/cm 3 in diamond and 5x10 15 at/cm 3 in SiC

Detection limit of phosphorus in diamond by high mass resolution secondary ion mass spectrometry (HMR‐SIMS)

International audienceIn diamond, Secondary Ion Mass Spectrometry (SIMS) is usually performed in order to detect and measure the depth distribution of impurities. The SIMS measurements are then performed by using parameters allowing high sensitivities. In the classical configuration for diamond analysis, the mass resolution is usually set at the lowest value and gives access to the concentration of most dopants. In the case of phosphorus, the detection limit is then in the range of a few 10 15 at/cm 3 (~20 ppb). In this work, we study several diamond samples and focus the SIMS detection on the secondary ions of masses 12 (carbon) and 31 (phosphorus). We show that SIMS analyses require high mass resolution (HMR) to accurately separate unexpected molecular ions detected at 31 a.m.u.. In such HMR-SIMS analyses, we improve the detection limit of phosphorus by one decade and achieve the value of 3x10 14 at/cm 3

Thick heavily boron doped CVD diamond films homoepitaxially grown on (111)-oriented substrates

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Thick and widened high quality heavily boron doped diamond single crystals synthetized with high oxygen flow under high microwave power regime

International audienceThe aim of this paper is to optimize the growth conditions of thick boron doped diamond single crystals, which requires the use of high microware power density to have high growth rate, in order to allow enlarging CVD deposited layers keeping both high boron doping level and high crystal quality. It is shown that the use of a high amount of oxygen (1 to 2%) in the gas phase leads to 1 mm lateral growth after the growth of 500 μm thick CVD diamond layer. Thus, the surface is increased from 10 mm² to 18 mm². The obtained films exhibit high crystal quality confirmed by Raman spectroscopy and confocal microscopy. Depending on the gas composition introduced in the reactor, the boron concentration varied between 5×1019 at/cm3 and 3×1020 at/cm3 as measured by SIMS

Sensitivity of photoelectron energy loss spectroscopy to surface reconstruction of microcrystalline diamond films

AbstractIn X-ray Photoelectron Spectroscopy (XPS), binding energies and intensities of core level peaks are commonly used for chemical analysis of solid surfaces, after subtraction of a background signal. This background due to photoelectron energy losses to electronic excitations in the solid (surface and bulk plasmon excitation, inter band transitions) contains valuable information related to the near surface dielectric function ɛ(ħω). In this work, the sensitivity of Photoelectron Energy Loss Spectroscopy (PEELS) is investigated using a model system, namely the well-controlled surface reconstruction of diamond. Boron-doped microcrystalline thin films with a mixture of (111) and (100) preferential orientations were characterized in the as-grown state, with a partially hydrogenated surface, and after annealing at 1150°C in ultra high vacuum. After annealing, the bulk (σ+π) plasmon of diamond at 34.5eV is weakly attenuated but no evidence for surface graphitization is observed near 6eV, as confirmed by electronic properties. Unexpected features which appear at 10±1eV and 19±1eV in the energy loss distribution are well described by simulation of surface plasmon excitations in graphite-like materials; alternatively, they also coincide with experimental inter band transition losses in some graphene layers. This comparative study shows that the PEELS technique gives a clear signature of weak effects in the diamond surface reconstruction, even in the absence of graphitization. It confirms the sensitivity of PEELS acquisition with standard XPS equipment as a complementary tool for surface analysis

Growth of thick and heavily boron-doped (113)-oriented CVD diamond films

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Determination of the phosphorus content in diamond using cathodoluminescence spectroscopy

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Phosphorus incorporation and activity in (100)-oriented homoepitaxial diamond layers

International audienceIn this work, we present a study about the homoepitaxial growth of phosphorus-doped diamond on (100) substrates. The growth was performed by microwave plasma assisted chemical vapor deposition (MPCVD) adding an organic precursor for phosphorus (tertiarybutylphosphine: TBP) in the gaseous phase. We show that phosphorus is incorporated in (100) chemical vapor deposition (CVD) diamond as proved by secondary ion mass spectrometry (SIMS). The recombination of excitons bound to phosphorus donors is observed by cathodoluminescence (CL) spectroscopy. The influence of the growth parameters on the phosphorus donor activity is investigated. We show that the [C*]/[H 2 ] ratio is a key parameter for controlling the P-donor activity when diamond is grown on (100) surfaces

Highly photostable NV centre ensembles in CVD diamond produced by using N 2 O as the doping gas

International audienceHigh density Nitrogen-Vacancy (NV) centre ensembles incorporated in plasma assisted CVD diamond are crucial to the development of more efficient sensing devices that use the properties of these luminescent defects. Achieving high NV doping with N2 as the dopant gas source during diamond growth is however plagued by the formation of macroscopic and point defects that quench luminescence. Moreover, such NVs are found to exhibit poor photostability under high laser powers. Although this effect can be harnessed to locally and durably switch off NV luminescence for data storage, it is usually undesirable for most applications. In this work the use of N2O as an alternative doping source is proposed. Much higher amounts of the doping gas can be added without significantly generating defects which allows the incorporation of perfectly photostable and higher density NV ensembles. This effect is believed to be related to the lower dissociation energy of the N2O molecule together with the beneficial effect of the presence of a low and controlled amount of oxygen near the growing surface