Open atomic layer deposition

An understanding of gas-phase and surface chemistry is particularly important to the next generation of MOVPE processes involving selective epitaxy [18] and atomic layer epitaxy (ALE) [19]. In the first process, the compound semiconductor is deposited selectively on substrate areas opened in a suitable masking material (e.g., SiOz). This is achieved by operating under conditions where nucleation occurs only on the substrates. Slight variations in processing environment and the presence of impurities can cause nucleation on the mask and result in loss of selectivity. 

Second, crystallographic engineering of the top atomic layer of the cores allows us to anploy a variety of core materials and so modification of the properties of supported PtML- Electrodeposition in nonaqueous solvents may open a fundamentally distinct area for the design and synthesis of core-shell nanoparticles. Considerable possibilities arise for studying core-shell interactions that are inaccessible in aqueous solutions. Our preliminary data show that yttrium nanoparticles, electro-deposited on carbon black in an organic solution, exhibited a certain unique interaction with codeposited Pt a 10-fold lower concentration of such Pt does not affect much the cathodic peak while it suppresses the dissolution of yttrium at the anode. On the other hand, we propose that carbon quantum dots, for example, small fragments of graphene oxides or carbon nanotubes, can support a... 

Fig. 2, Process steps used to produce the structure shown in Fig. 1 (a) A film of SiO > lias been formed by oxidizing the silicon and a layer of photoresist has been deposited on the SiCd (b) Shading shows a region of the photoresist that has been exposed to light and thereby made more soluble, (c) The exposed photoresist has been removed. (cl) An etchant that reacts with the SKF. but not with the photoresist, lias been removed, (e) Anodier solvent has been used to remove the unexposed photoresist, (f) Donor atoms have diffused into the silicon through the opening in the SiCr to produce an a-type region, fg) Additional masking steps, not shown, have permitted aluminum to be evaporated onto the diode in a pattern that forms a contact to the n region of the diode. (See Fig. 1 for legend)...

The divergence between the elemental composition at the topmost layer and that in the bulk is appreciated best when the atom-percent composition of Pt (or Co) at the alloy surface is plotted as a function of the monolayer-percent composition of Pt (or Co) in the bulk. Such a plot, which represents the phase diagram of the outermost-layer Pt-Co alloy, is shown in Fig. 7 the open circles are data for when Ptwas deposited initially, whereas the... 

---