The method that is commonly used for determining the flat-band voltage (VFB) and the flat-band capacitance (CFB) of metal oxide semiconductor (MOS) capacitors depends on many parameters and can only be used in the case of low interface trap density (Dit) when the capacitance–voltage measurements are carried out at high frequencies. This paper demonstrates a new and simple method for determining VFB and CFB. The method is based on the point of inflection in the capacitance–voltage curve. This method does not require the knowledge of material or experimental parameters and can be used on high Dit and high border trap density MOS structures at all frequencies.

To better understand the formation mechanism of ohmic contacts to GaN-based heterostructure field effect transistors, we have compared in detail Ti/Al/Ti/Au and Ti/Al/Ti/TiN contacts. Transmission electron microscopy and electron dispersive X-ray spectroscopy revealed that following anneal, TiN islands penetrated through the AlGaN barrier, as already well known, in the gold-based ohmic contacts but not in the gold-free contacts. We hence conclude that gold facilitates the formation of the TiN islands and propose that the role of gold is extraction of gallium from the semiconductor, providing a gallium depleted region for TiN island formation. For the case of the gold-free contacts, a 8 nm thick semi continuous TiN layer was formed following 900 °C anneal. A 2 nm thick TiN layer was observed in the as deposited samples and remained intact after anneal up to 825 °C. The different ohmic contact formation mechanism of gold-based and gold-free contacts is also manifested by our finding that a discontinuous AlN nitride spacer layer between the barrier and the bulk may lead to non-uniformity in contact behavior across the wafer in the case of gold-free contacts. For gold-based contacts, ohmic contact behavior was uniform across the wafer.

Atomic layer deposited titanium dioxide (ALD-TiO2) 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 x 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 TiO2 significantly improves reliability of anodes, yielding an adhesion energy of 6.02 ± 0.5 J/m2, more than double the adhesion energy measured in the absence of an ALD-TiO2 protection layer. These results indicate the importance of catalyst adhesion to an interposed protection layer in promoting operational stability of high efficiency semiconducting anodes during solar-driven water splitting.

The effect of Al2O3 atomic layer deposition (ALD) temperature on the border trap density (Nbt) of Al2O3/InGaAs gate stacks is investigated quantitatively, and we demonstrate that lowering the trimethylaluminum (TMA)/water vapor ALD temperature from 270 °C to 120 °C significantly reduces Nbt. The reduction of Nbt coincides with increased hydrogen incorporation in low temperature ALD-grown Al2O3 films during post-gate metal forming gas annealing. It is also found that large-dose (∼6000 L) exposure of the In0.53Ga0.47As (100) surface to TMA immediately after thermal desorption of a protective As2 capping layer is an important step to guarantee the uniformity and reproducibility of high quality Al2O3/InGaAs samples made at low ALD temperatures.

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Indium outdiffusion and leakage degradation in metal/Al2O3/In0.53Ga0.47As capacitors Appl.Hard x-ray photoelectron spectroscopy study of As and Ga out-diffusion in In0.53Ga0.47As/Al2O3 film systems Appl. Phys. Lett. 101, 061602 (2012); 10.1063/1.4745207Lanthanum aluminate by atomic layer deposition and molecular beam epitaxy

A thin semiconducting NiO film is exposed to NO2 at room temperature. This exposure causes a work function change at the surface of the film due to adsorption of the NO2 molecules. It is found that there is a strong dependence of the adsorptivity, i.e., the amount of work function change per unit time, on the magnitude of an electrical field that is applied perpendicular to the film surface. This induced adsorptivity change is known as the electroadsorptive effect. In order to modulate the adsorptivity significantly, the electrical field strength must exceed 104 V/cm. This requirement can be achieved by using hybrid suspended gate field effect transistors with an air gap height below 1 μm.

One of the main challenges in the path to incorporating InGaAs based metal-oxide-semiconductor structures in nanoelectronics is the passivation of high-k/InGaAs interfaces. Here, the oxygen scavenging effect of thin Ti layers on high-k/InGaAs gate stacks was studied. Electrical measurements and synchrotron X-ray photoelectron spectroscopy measurements, with in situ metal deposition, were used. Oxygen removal from the InGaAs native oxide surface layer remotely through interposed Al2O3 and HfO2 layers observed. Synchrotron X-ray photoelectron spectroscopy has revealed a decrease in the intensity of InOx features relative to In in InGaAs after Ti deposition. The signal ratio decreases further after annealing. In addition, Ti 2p spectra clearly show oxidation of the thin Ti layer in the ultrahigh vacuum XPS environment. Using capacitance-voltage and conductance-voltage measurements, Pt/Ti/Al2O3/InGaAs and Pt/Al2O3/InGaAs capacitors were characterized both before and after annealing. It was found that the remote oxygen scavenging from the oxide/semiconductor interface using a thin Ti layer can influence the density of interface traps in the high-k/InGaAs interface.