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The elastic properties of Mo2BC were studied using ab initio calculations. The calculated bulk modulus of 324 GPa is 45% larger than that of Ti0.25Al0.75N and 14% smaller than that of c-BN, indicating a highly stiff material. The bulk modulus (B) to shear modulus (G) ratio is 1.72 at the transition from brittle to ductile behaviour. This, in combination with a positive Cauchy pressure (c12 − c44), suggests moderate ductility. When compared with a typical hard protective coating such as Ti0.25Al0.75N (B = 178 GPa; B/G = 1.44; negative Cauchy pressure), Mo2BC displays considerable potential as protective coating for metal cutting applications. In order to test this proposal, Mo2BC thin films were synthesized using dc magnetron sputtering from three plasma sources on Al2O3(0 0 0 1) at a substrate temperature of ∼900 °C. The calculated lattice parameters are in good agreement with values determined from x-ray diffraction. The measured Young's modulus values of ∼460 ± 21 GPa are in excellent agreement with the 470 GPa value obtained by calculations. Scanning probe microscopy imaging of the residual indent revealed no evidence for crack formation as well as significant pile-up, which is consistent with the moderate plasticity predicted. The apparent contradiction between moderate ductility on the one hand and indentation hardness values of 29 GPa can be understood by considering the electronic structure particularly the extreme anisotropy. The presence of stiff Mo–C and Mo–B layers with metallic interlayer bonding enables this intriguing and unexpected property combination.

SiO2 is the most widely used dielectric material but its growth or deposition involves high thermal budgets or suffers from shadowing effects. The low-temperature method presented here (150 degrees C) for the preparation of SiO2 by thermal atomic layer deposition (ALD) provides perfect uniformity and surface coverage even into nanoscale pores, which may well suit recent demands in nanoelectronics and nanotechnology. The ALD reaction based on 3-aminopropyltriethoxysilane, water, and ozone provides outstanding SiO2 quality and is free of catalysts or corrosive by-products. A variety of optical, structural, and electrical properties are investigated by means of infrared spectroscopy, UV-Vis spectroscopy, secondary ion mass spectrometry, capacitance-voltage and current-voltage measurements, electron spin resonance, Rutherford backscattering, elastic recoil detection analysis, atomic force microscopy, and variable angle spectroscopic ellipsometry. Many features, such as the optical constants (n, k) and optical transmission and surface roughness (1.5 A degrees), are found to be similar to thermal oxide quality. Rapid thermal annealing (RTA) at 1000 degrees C is demonstrated to significantly improve certain properties, in particular by reducing the etch rate in hydrofluoric acid, oxide charges, and interface defects. Besides a small amount of OH groups and a few atomic per mille of nitrogen in the oxide remaining from the growth and curable by RTA no impurities could be traced. Altogether, the data point to a first reliable low temperature ALD-growth process for silicon dioxide

Lithium phosphate, Li 3 PO 4 , has been considered a potential electrolyte material for lithium ion batteries and CO 2 sensors in particular if the films can be made dense and of high quality already at low thickness. In this work, Li 3 PO 4 thin films were deposited by atomic layer deposition (ALD) between 225 and 350 • C using trimethyl phosphate and either of the two lithium sources, namely lithium hexamethyldisilazide or lithium tert-butoxide. The deposited films showed slightly crystalline Li 3 PO 4 structure in X-ray diffraction and the elastic recoil detection analysis confirmed this stoichiometry with some carbon and hydrogen impurities. The crystallinity and thermal stability of the films at elevated temperatures in N 2 were also examined. The long term stability of the deposited Li 3 PO 4 films under ambient air may be an issue for the applicability of these processes. Lithium phosphate, Li 3 PO 4 , can be applied as an electrolyte in solid state lithium ion batteries 1-3 and CO 2 gas sensors. 4-6 Also optical humidity sensors based on Li 3 PO 4 have been presented recently. 7 Thin Li 3 PO 4 film has also been used as an interfacial layer between LiCoO 2 electrode and solid polymer electrolyte in solid state lithium ion battery. 8 Crystallization of Li 3 PO 4 greatly decreases the ionic conductivity: amorphous Li 2.7 PO 3.9 has an ionic conductivity of 6.6 × 10 −8 S/cm while the polycrystalline γ-Li 3 PO 4 has been extrapolated to be highly resistive with as low conductivity as 4.2 × 10 −18 S/cm at 25 • C. 9 Even if the ionic conductivity is only moderate, amorphous Li 3 PO 4 is still a potential electrolyte material provided it can be made dense already at low thickness.In lithium ion battery applications the 3D structuring of the materials would be a way to effectively increase the energy storage capacity by increasing the specific surface area. 10, 11 Atomic layer deposition (ALD) 12-15 may prove to be useful for depositing thin films on demanding 3D structures as films grown by ALD inherently possess good conformality and uniformity because of the alternating, saturative precursor doses and self-limiting surface reactions. The resulting accurate thickness controllability and repeatability of the films is a major benefit of the layer by layer approach used in ALD. Some of the electrolyte material candidates for 3D batteries include for example Li 3 PO 4 and nitrogen mixed lithium phosphate known as LiPON. 10,11 ALD processes for phosphate films are very few in number, although aluminum phosphate thin films have been deposited already in the 90's. 16,17 Besides aluminum phosphate, only ALD of calcium phosphate has been published. 18 Also lithium containing ALD processes were absent until recent reports on ALD of lithium hydroxide, lithium carbonate, lithium aluminate, lithium silicate, lithium lanthanate and lithium lanthanum titanates. [19][20][21][22][23] In addition, ALD of LiFePO 4 and Ca:LaPO 4 materials have been recently presented. 24,25 Here we report ALD growth and characterization of lithium...

The influence of the high-temperature annealing ambient, i.e., N 2 and Ar on size controlled Si nanocrystals ͑NCs͒ ranging from ϳ2 to ϳ6 nm embedded in SiO 2 has been investigated in detail. Generally, N 2 annealing is proven to be beneficial as the dangling bond density ͑P b defects at the NC/ SiO 2 interface͒ is about half, accompanied by a doubled photoluminescence ͑PL͒ intensity. The PL blueshift of N 2 annealed samples compared to Ar-annealed samples ͑N-blueshift͒ was found to be pronounced only for small NCs whereas it appears to be insignificant for larger NCs. The origin of this N-blueshift was previously attributed to a growth suppression of the NCs by the presence of N during the annealing process. However, no evidence for this assumption is found by time-resolved PL, as the luminescence decay times are similar despite considerable N-blueshift. The exact location of the N incorporated during annealing was investigated by time-of-flight-SIMS and electron-spin resonance. Besides the distinct N enrichment in the NC layer, the K 0 center ͑ • Si ϵ N 3 ͒ was detected indicating the formation of an interfacial N layer at the NC/ SiO 2 interface. Elastic recoil detection analysis enabled the quantification of the incorporated N as well as the excess Si. Combined with transmission electron microscopy analysis ͑determination of NC size͒ the calculation of the NC density per superlattice layer and the thickness of the interfacial N layer were achieved. It turns out that ϳ5 ϫ 10 14 N atoms cm −2 exist at the NC surface, which is well in accordance to the optimum value of the bulk Si/ SiO 2 interface. These results strongly support our recently suggested explanation for the N-blueshift that is based on an increased NC band gap by the influence of interfacial N on the polarity of the surface terminating groups.