Epitaxial second order

Apart from the (disordered and ordered) monolayer phases of tetraeene/ Ag(l 11), a second ordered phase is observed at higher coverage. This so-called (3-phase [69] is a bilayer with an extremely complex structure which is discussed elsewhere [49]. There are two notable facts about this phase. Firstly, the first layer of the bilayer is not the flat lying monolayer phase (a-phase). Rather, under the influence of the attractive intermolecular interactions with molecules in the seeond layer, the first layer re-orders and (partly) tilts up. This behaviour is markedly different from PTCDA, where the first layer forces the second layer into its epitaxial structure. This disparity indicates once more that for the two systems the weighting between intermolecular and interfacial interactions is different. Seeondly, a detailed analysis of single-molecule spectra in the (3-phase shows that the moleeular environment has a very strong influence on the electronic properties of individual molecules, even for molecules far away from the metal. 

In thin films of nanostructured ZnO ( 200 nm thick) grown by PLD, a significant enhancement of% compared to the epitaxially grown ZnO films has been observed with THG efficiencies as high as 1.3% at Xa, = 1250 nm, corresponding to = (1.4 0.7) X 10 esu [217]. This enhancement has been attributed to the reduced dimensionality due to nanocrystalline structure, which has been shown to enhance also the second-order nordinearities as discussed above. Such high efficiency of nonlinear optical conversion creates a potential for nanostructures ZnO thin films to be used in nonlinear optical devices. 

Numerous works have been implemented on tellurium electrochemistry and its adsorption at metal surfaces. The morphological structures of electrodeposited Te layers at various stages of deposition (first UPD, second UPD, and bulk deposition) are now well known [88-93]. As discussed in the previous paragraphs, Stickney and co-workers have carried out detailed characterizations of the first Te monolayer on Au single-crystal surfaces in order to establish the method of electrochemical atomic layer epitaxy of CdTe. 

A silicon dioxide layer 3 is formed on an insulating CdTe substrate 1. A photo-resist coating 5 is formed over the silicon dioxide layer. The photo-resist layer is patterned and the silicon layer is partly etched away. The photo-resist layer is removed and a film of HgCdTe 9 of a first mercury to cadmium ratio is deposited by liquid phase epitaxial deposition over the entire surface of the substrate. The HgCdTe film is only formed at regions where the CdTe substrate is exposed and does not adhere to the silicon dioxide. Next, the silicon dioxide layer is removed. In order to increase the window of frequency response of the detectors, the process is repeated using a second mercury to cadmium ratio different from the first ratio. 

In the past, several reviews have summarized the different synthesis and growth techniques developed to improve the degree of crystallinity of GaN films or the bulk phase [43, 105, 130, 132-137]. The two main categories of preparation methods address diEFerent aims of appUcations the first concerns the epitaxial deposition of highly ordered films on substrates for blue LEDs or lasers the second other focuses on the growth of large single crystals for use as substrates or wafers. In both cases the main problem is the decomposition of GaN under elevated temperatures. 

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