InGaAs is a promising alternative channel material to Si for sub‐22 nm node technology because of its low electron effective mass (m*) hence high electron velocities. We report a gate‐first MOSFET process with self‐aligned source/drain formation using non‐selective MBE re‐growth, suitable for realizing high performance scaled III‐V MOSFETs. A W/Cr/SiO2 gate stack was defined on thin (4 nm/2.5 nm) InGaAs/InP channel by an alternating selective dry etch technique. A 5 nm Al2O3 layer was used as gate dielectric. An InAlAs bottom barrier provided vertical confinement of the channel. An in‐situ H cleaning of the wafer leaves an epi‐ready surface suitable for MBE or MOCVD regrowth. Source/Drain region were defined by non‐selective MBE regrowth and in situ molybdenum contacts. First generation of devices fabricated using this process showed extremely low drive current of 2 μA/μm. The drive current was limited by an extremely high source resistance. A regrowth gap between source/drain and gate was the cause for high source resistance. The gap in the regrowth was because of low growth temperature (400 °C). A modified high temperature growth technique resolved the problem. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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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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