Lior Kornblum

Experimental evidence for the correlation between the weak inversion hump and near midgap states in dielectric/InGaAs interfaces

Temperature dependent capacitance–voltage (C-V) and conductance-voltage (G-V) measurements were performed to obtain activation energies (EA) for weak inversion C-V humps and parallel conductance peaks in Al2O3/InGaAs and Si3N4/InGaAs gate stacks. Values of 0.48 eV (slightly more than half of the band gap of the studied In0.53Ga0.47As) were obtained for EA of both phenomena for both gate dielectrics studied. This indicates an universal InGaAs behavior and shows that both phenomena are due to generation-recombination of minority carriers through near midgap located interface states. The C-V hump correlates with the interface states density (Dit) and can be used as a characterization tool for dielectric/InGaAs systems.

A high density two-dimensional electron gas in an oxide heterostructure on Si (001)

We present the growth and characterization of layered heterostructures comprised of LaTiO3 and SrTiO3 epitaxially grown on Si (001). Magnetotransport measurements show that the sheet carrier densities of the heterostructures scale with the number of LaTiO3/SrTiO3 interfaces, consistent with the presence of an interfacial 2-dimensional electron gas (2DEG) at each interface. Sheet carrier densities of 8.9 × 1014 cm−2 per interface are observed. Integration of such high density oxide 2DEGs on silicon provides a bridge between the exceptional properties and functionalities of oxide 2DEGs and microelectronic technologies.

Investigation of the band offsets caused by thin Al2O3 layers in HfO2 based Si metal oxide semiconductor devices

Ultrathin dielectric capping layers are a prominent route for threshold voltage control in advanced Si devices. In this work the position of an Al2O3 layer inside a HfO2-based stack is systematically varied and investigated following a low and a high temperature anneal. Electrical results are compared with a sub-nanometer resolution materials characterization, showing a diffusion of Al to the bottom HfO2 interface. A correlation is found between the presence of Al at the bottom interface and a flatband voltage increase. Based on these findings, we propose to use the position of the Al2O3 for fine-tuning the threshold voltage.

Effect of H on interface properties of Al2O3/In0.53Ga0.47As

We report that depositing Al2O3 on InGaAs in an H-containing ambient (e.g., in forming gas) results in significant reduction of interface-trap density and significantly suppressed frequency dispersion of accumulation capacitance. The results of the inelastic electron tunneling spectroscopy study reveal that strong trap features at the Al2O3/InGaAs interface in the InGaAs band gap are largely removed by depositing Al2O3 in an H-containing ambient. Transmission electron microscopy images and x-ray photoelectron spectroscopy data shed some light on the role of hydrogen in improving interface properties of the Al2O3/In0.53Ga0.47As gate stack.

Fermi level tuning using the Hf-Ni alloy system as a gate electrode in metal-oxide-semiconductor devices

Hf-Ni alloys are studied as a gate electrode for metal-oxide-semiconductor devices. The Hf-Ni solid-state amorphization couple encompasses several metallurgical phenomena which are investigated at the nanoscale and are correlated with the macroscopic electrical properties of devices. The dependence of the Fermi level position on the alloy composition is studied both on SiO2 and on HfO2. In order to isolate the effects of interfacial and dielectric charges and dipoles, the dependence of the vacuum work-function values on the composition is also studied. The Fermi level positions of the alloys do not depend linearly on the average composition of the alloys and are strongly affected by Hf enrichment at the HfNix/dielectric interface and the HfNix surface. We note a constant shift of 0.4 eV in the Fermi level position on HfO2 compared to SiO2. In addition, characterization of the composition, structure, and morphology reveals Kirkendall voids formation when the bottom layer consists of Ni, and an oxygen-scave...

Oxide 2D electron gases as a route for high carrier densities on (001) Si

Two dimensional electron gases (2DEGs) formed at the interfaces of oxide heterostructures draw considerable interest owing to their unique physics and potential applications. Growing such heterostructures on conventional semiconductors has the potential to integrate their functionality with semiconductor device technology. We demonstrate 2DEGs on a conventional semiconductor by growing

Probing the electrostatics of self-assembled monolayers by means of beveled metal-oxide-semiconductor structures

GdTiO_3-SrTiO_3

The electrostatics of Ta2O5 in Si-based metal oxide semiconductor devices

on silicon. Structural analysis confirms the epitaxial growth of heterostructures with abrupt interfaces and a high degree of crystallinity. Transport measurements show the conduction to be an interface effect, with

Effect of hydrogen on the chemical bonding and band structure at the Al2O3/In0.53Ga0.47As interface

\sim 9\times 10^{13} \; cm^{-2}

Electronic transport of titanate heterostructures and their potential as channels on (001) Si

electrons per interface. Good agreement is demonstrated between the electronic behavior of structures grown on Si and on an oxide substrate, validating the robustness of this approach to bridge between lab-scale samples to a scalable, technologically relevant materials system.