Lattice mismatch with a substrate and difference in coefficient of thermal expansion to the substrate induces stress and deformations in crystalline structure of epitaxially grown layers. In this work, we present results of structural study of gadolinium oxide and erbium oxide grown on silicon (111) substrate applying X-ray diffraction at room temperature and during in-situ heating up to 1273 K. The layers are almost fully relaxed at room temperature. Only minor tetragonal distortion of the crystal lattice was indirectly detected. No thermal induced stress relaxation occurs in the oxide layer during the in-situ heating and cooling procedure though strong tetragonal distortion of the oxide lattice due to thermal expansion difference with silicon. The time-domain thermo-reflectance measurements reveal that thermal conductivity of the rare earth oxides is approximately five times higher than that of silicon dioxide.Rare-earth-metal oxides (REO) grown epitaxially on silicon have attracted much attention primary because of their applications as gate dielectrics for metal-oxide-semiconductor (MOS) devices. 1-4 Additionally, as was demonstrated in some works, 5,6 single crystal rareearth oxides can be considered as a lattice mismatch accommodating buffer for growth of alternative semiconductors on a silicon substrate or for epitaxial semiconductor on insulator (SOI) structures applying from few tens to micrometers thick oxide layers. Stable crystal structure and stoichiometry in temperature range typical for epitaxy and subsequent semiconductor device processing are the main requirements for the buffer dielectric material. According to comprehensive studies of polymorphism of rare-earth oxides by Warshaw et al.,7 Adachi and Imanaka, 8 large ionic radius rare earth sesquioxides (Nd 2 O 3 , Pr 2 O 3 and La 2 O 3 ) have stable hexagonal structure in the range of temperatures typical for epitaxial process. As it was shown in works of other groups that performed epitaxy of silicon on hexagonal praseodymium oxide, 9-11 transferring of the crystallographic stacking sequence from the hexagonal structure of the oxide to cubic structure of semiconductor causes crystal defects in the epitaxially grown semiconductor layer. For this reason, oxides with cubic crystal structure are more preferable for growth of semiconductor on insulator structures. Additionally, lattice constant mismatch between epitaxial dielectric layer and silicon substrate should be small in order to avoid formation of dislocations that propagate up to surface of a grown layer as was demonstrated for Sc 2 O 3 12 and for to cubic bixbyite structure close related calcium fluoride 13 grown on Si(111). From the group of rare-earth oxides, particularly of interest for application as materials for buried dielectric layers for SOI application are the sesquioxides with stable cubic structure and stable oxidation state: Gd 2 O 3 , Er 2 O 3 , Yb 2 O 3 , Lu 2 O 3 . However, their crystal lattice is smaller if compared to that of twice of silicon (from about 0.5% for Gd 2 O...

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Growth of GaN on rare earth oxide (REO) buffers grown on silicon (111) was performed. A novel low temperature buffer layer was developed in order to suppress the decomposition of the REO buffer under hydrogen flow during MOCVD. GaN films, grown by this technique, exhibit smooth surface morphologies. XRD studies reveal the formation of an ErN layer during growth. 10.1149/05804.0455ecst ©The Electrochemical Society ECS Transactions, 58 (4) 455-461 (2013) 455 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 138.251.14.35 Downloaded on 2015-06-10 to IP

This paper presents a novel ole-MCM-LID-concept for fully integrated opto-electronic MCM-packaging aiming at: very low cost, very high interconnect density and high performance. The polymer thin film materials technology allowing the integration of optical waveguides and high density electrical interconnects in just 3 thin film layers is also discussed in terms of chemistry, processes and properties. Very good processability and planarization of the new inorganic-organic photo-polymers, ORMOCERs, (ORganically Modified CERamics) in combination with a much lower post-curing temperature (120 "C -170 "C) than alternative materials (such as polyimide and benzocyclobutene) enables the use of low cost polymer substrates such as FR-4 epoxy.Novel surface mountable waveguide-connectors for passive precision alignment, compatible with standard MTopto-connectors can be used for coupling light in and out from the ole-MCM-LID'S. In the demonstrator, laser-arrays (VCSEL's) and photodiode-arrays are flip-chip mounted above UV-excimer laser ablated 45-degree mirrors in the waveguides. Driver-chips and passive components are wirebonded and surface mounted respectively.The modules are also supplied with microvias in the FR4epoxy-substrate connecting to a ball grid array (BGA) underneath. The need of any extra package for connection to next packaging level is thus eliminated. In conclusion the versatility and the low-cost potential of the presented technologies are emphasized.

Ternary and binary rare-earth oxides that are used as a template buffer, which accommodates the crystal lattice mismatch between substrate and a semiconductor layer, are discussed here. The oxides were grown on Si(111) substrates and exhibit the cubic bixbyite crystal structure. Stabilization of the cubic bixbyite structure of ternary erbium-neodymium oxide and lanthanum oxide was analyzed using structural investigation of the epitaxially grown oxides and ab initio density functional theory calculations. The authors demonstrate that despite the more energetically favorable hexagonal structure of bulk lanthanum oxide a pseudomorphic single crystal cubic lanthanum oxide layer grows under nonequilibrium conditions of a molecular beam epitaxy process on gadolinium oxide. Growth of hexagonal lanthanum oxide begins when the critical thickness of the layer is reached. Germanium was epitaxially grown on the cubic bixbyite lanthanum sesquioxide. Due to a higher surface energy, germanium starts to grow in the form of twinned islands on the oxide layer that later merge, forming a closed layer. X ray diffraction reveals mostly single crystal structure of the germanium layer with stacking twins located only at the interface with the lanthanum oxide layer.