Nanocrystallite Seeding of Metastable Ferroelectric Phase Formation in Atomic Layer-Deposited Hafnia-Zirconia Alloys.

Hafnia-based ferroelectric thin films are promising for semiconductor memory and neuromorphic computing applications. Amorphous, as-deposited, thin-film binary alloys of HfO and ZrO transform to the metastable, orthorhombic ferroelectric phase during post-deposition annealing and cooling. This transformation is generally thought to involve formation of a tetragonal precursor phase that distorts into the orthorhombic phase during cooling.

Link between Gas Phase Reaction Chemistry and the Electronic Conductivity of Atomic Layer Deposited Titanium Oxide Thin Films.

In situ monitoring of gas phase composition reveals the link between the changing gas phase chemistry during atomic layer deposition (ALD) half-cycle reactions and the electronic conductivity of ALD-TiO thin films. Dimethylamine ((CH)NH, DMA) is probed as the main product of both the TDMAT and water vapor half-reactions during the TDMAT/HO ALD process. In-plane electronic transport characterization of the ALD grown films demonstrates that the presence of DMA, a reducing agent, in the ALD chamber throughout each half-cycle is correlated with both an increase in the films' electronic conductivity, and observation of titanium in the 3+ oxidation state by ex situ X-ray photoelectron spectroscopy analysis of the films.

In-situ reflectometry to monitor locally-catalyzed initiation and growth of nanowire assemblies.

We investigate in-situ laser reflectometry for measuring the axial growth rate in chemical vapor deposition of assemblies of well-aligned vertical germanium nanowires grown epitaxially on single crystal substrates. Finite difference frequency domain optical simulations were performed in order to facilitate quantitative analysis and interpretation of the measured reflectivity data. The results show an insensitivity of the reflected intensity oscillation period to nanowire diameter and density within the range of experimental conditions investigated.

Understanding the Mechanism of Electronic Defect Suppression Enabled by Nonidealities in Atomic Layer Deposition.

Silicon germanium (SiGe) is a multifunctional material considered for quantum computing, neuromorphic devices, and CMOS transistors. However, implementation of SiGe in nanoscale electronic devices necessitates suppression of surface states dominating the electronic properties. The absence of a stable and passive surface oxide for SiGe results in the formation of charge traps at the SiGe-oxide interface induced by GeO.

Engineering High- k/SiGe Interface with ALD Oxide for Selective GeO Reduction.

Suppression of electronic defects induced by GeO at the high- k gate oxide/SiGe interface is critical for implementation of high-mobility SiGe channels in complementary metal-oxide-semiconductor (CMOS) technology. Theoretical and experimental studies have shown that a low defect density interface can be formed with an SiO -rich interlayer on SiGe. Experimental studies in the literature indicate a better interface formation with AlO in contrast to HfO on SiGe; however, the mechanism behind this is not well understood.

Dynamic thermal emission control with InAs-based plasmonic metasurfaces.

Thermal emission from objects tends to be spectrally broadband, unpolarized, and temporally invariant. These common notions are now challenged with the emergence of new nanophotonic structures and concepts that afford on-demand, active manipulation of the thermal emission process. This opens a myriad of new applications in chemistry, health care, thermal management, imaging, sensing, and spectroscopy.

The Role of Catalyst Adhesion in ALD-TiO Protection of Water Splitting Silicon Anodes.

Atomic layer deposited titanium dioxide (ALD-TiO) has emerged as an effective protection layer for highly efficient semiconductor anodes which are normally unstable under the potential and pH conditions used to oxidize water in a photoelectrochemical cell. The failure modes of silicon anodes coated with an Ir/IrO oxygen evolution catalyst layer are investigated, and poor catalyst/substrate adhesion is found to be a key factor in failed anodes. Quantitative measurements of interfacial adhesion energy show that the addition of TiO significantly improves reliability of anodes, yielding an adhesion energy of 6.

Ultralow Defect Density at Sub-0.5 nm HfO/SiGe Interfaces via Selective Oxygen Scavenging.

The superior carrier mobility of SiGe alloys make them a highly desirable channel material in complementary metal-oxide-semiconductor (CMOS) transistors. Passivation of the SiGe surface and the associated minimization of interface defects between SiGe channels and high- k dielectrics continues to be a challenge for fabrication of high-performance SiGe CMOS. A primary source of interface defects is interfacial GeO .

Dielectric Breakdown in Chemical Vapor Deposited Hexagonal Boron Nitride.

Insulating films are essential in multiple electronic devices because they can provide essential functionalities, such as capacitance effects and electrical fields. Two-dimensional (2D) layered materials have superb electronic, physical, chemical, thermal, and optical properties, and they can be effectively used to provide additional performances, such as flexibility and transparency. 2D layered insulators are called to be essential in future electronic devices, but their reliability, degradation kinetics, and dielectric breakdown (BD) process are still not understood.

Low temperature thermal ALD of a SiN interfacial diffusion barrier and interface passivation layer on SiGe(001) and SiGe(110).

Atomic layer deposition of a silicon rich SiN layer on SiGe(001), SiGe(001), and SiGe(110) surfaces has been achieved by sequential pulsing of SiCl and NH precursors at a substrate temperature of 285 °C. XPS spectra show a higher binding energy shoulder peak on Si 2p indicative of SiONCl bonding while Ge 2p and Ge 3d peaks show only a small amount of higher binding energy components consistent with only interfacial bonds, indicating the growth of SiON on the SiGe surface with negligible subsurface reactions. Scanning tunneling spectroscopy measurements confirm that the SiN interfacial layer forms an electrically passive surface on p-type SiGe(001), SiGe(110), and SiGe(001) substrates as the surface Fermi level is unpinned and the electronic structure is free of states in the band gap.

Interface Defect Hydrogen Depassivation and Capacitance-Voltage Hysteresis of AlO/InGaAs Gate Stacks.

We investigate the effects of pre- and postatomic layer deposition (ALD) defect passivation with hydrogen on the trap density and reliability of AlO/InGaAs gate stacks. Reliability is characterized by capacitance-voltage hysteresis measurements on samples prepared using different fabrication procedures and having different initial trap densities. Despite its beneficial capability to passivate both interface and border traps, a final forming gas (H/N) anneal (FGA) step is correlated with a significant hysteresis.

Characterization of the photocurrents generated by the laser of atomic force microscopes.

The conductive atomic force microscope (CAFM) has become an essential tool for the nanoscale electronic characterization of many materials and devices. When studying photoactive samples, the laser used by the CAFM to detect the deflection of the cantilever can generate photocurrents that perturb the current signals collected, leading to unreliable characterization. In metal-coated semiconductor samples, this problem is further aggravated, and large currents above the nanometer range can be observed even without the application of any bias.