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Cuprous oxide (Cu2O) is actively studied as a prototypical material for energy conversion and electronic applications. Here we reduce the growth temperature of phase pure Cu2O thin films to 300 °C by intentionally controlling solely the kinetic parameter (total chamber pressure, Ptot) at fixed thermodynamic condition (0.25 mTorr pO2). A strong non-monotonic effect of Ptot on Cu-O phase formation is found using high-throughput combinatorial-pulsed laser deposition. This discovery creates new opportunities for the growth of Cu2O devices with low thermal budget and illustrates the importance of kinetic effects for the synthesis of metastable materials with useful properties.

Acceptor‐doped barium cerate perovskite oxides act as high temperature proton conducting ceramics, which can be utilized in solid oxide fuel cells, hydrogen separation membranes, and other electrochemical devices. One of the major issues in their fabrication is the formation of second phases during sintering of these perovskite oxides. In this work, the formation of a second phase is investigated with an aim to understand its influence on the properties of the parent perovskite oxide and also the necessity for its removal. BaCe0.8Y0.2O3−δ (BCY20) was synthesized via a polymeric sol–gel method and characterized by X‐ray diffraction, scanning electron microscopy, and micro‐Raman spectroscopy. Formation of the second phase on the surface of the sintered pellets (sintering temperature >1250°C for 24 h) was identified to be yttria‐doped ceria (Y0.2Ce0.8O1.9). A mechanism for the formation of the second phase is proposed. The formation of second phase was prevented by sintering the pellets in a powder bath of the same composition as the parent perovskite oxide. From impedance spectroscopy measurements of pellets sintered with and without the powder bath, it was found that the second phase (in the pellet sintered without powder bath) has a negative effect on the bulk ionic conductivity of the pellet.

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Titanium nitride (TiN), a refractory material is actively been used as a diffusion barrier in Middle-ofthe-Line (MOL) contacts. In the typical MOL stack (titanium (Ti)/TiN/tungsten(W)), it acts as a fluorine (F) diffusion barrier and also as an adhesion layer to W. During W deposition, F from W precursor chemistry can react with Ti to form a highly resistive titanium fluoride (TiFx) compound. The formation of TiFx creates >200% volume expansion which can result in cracks on the TiN layer or W delamination. In order to be an effective diffusion barrier layer, TiN has to be dense which demands a critical thickness. In this work, we study the materials properties of ALD TiN as a function of thickness in the range 11 -35 Å. We found a linear increase in resistivity of TiN on Ti with thickness. Columnar structured microstructure was observed for TiN films with thickness 30.4 and 34.7 Å. These films were also found to be slightly denser. TEM electron diffraction indicated that the 34.7 Å film is preferentially oriented along [111]. The roughness of the film increases with thickness. Three roughness zones with different crystallization modes have been identified which indicates thickness dependent crystallization. From our study, it is clear that in addition to density, the formation of preferential orientation of TiN might play a role for critical thickness requirement.

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