Fabrication of Silicon Nanowire Metal-Oxide-Semiconductor Capacitors with Al2O3/TiO2/Al2O3 Stacked Dielectric Films for the Application to Energy Storage Devices

Silicon nanowire (SiNW) metal-oxide-semiconductor (MOS) capacitors with Al2O3/TiO2/Al2O3 (ATA) stacked dielectric films were fabricated by metal-assisted chemical etching (MACE) and atomic layer deposition (ALD). High-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) images revealed that SiNWs were conformally coated with ATA although the cross-sectional shapes of MACE-SiNWs were non-uniform and sharp spikes can be seen locally. The dielectric capacitance density of 5.9 μF/cm2 at V = −4 V of the perfect accumulation region was achieved due to the combination of the large surface area of the SiNW array and the high dielectric constant of ATA. The capacitance changed exponentially with the voltage at V < −4.3 V and the capacitance of 84 μF/cm2 was successfully achieved at V = −10 V. It was revealed that not only 3D structure and high-k material but also local nanostructure of SiNWs and stacked dielectric layers could contribute to the considerable high capacitance.

Download Full-text

Effect of Metal - Silicon Nanowire Contacts on the Performance of Accumulation Metal Oxide Semiconductor Field Effect Transistor

MRS Proceedings ◽

10.1557/proc-1144-ll06-02 ◽

2008 ◽

Vol 1144 ◽

Author(s):

Pranav Garg ◽

Yi Hong ◽

Md. Mash-Hud Iqbal ◽

Stephen J. Fonash

Keyword(s):

Metal Oxide ◽

Silicon Nanowires ◽

Field Effect ◽

Field Effect Transistor ◽

Silicon Nanowire ◽

Metal Oxide Semiconductor ◽

Oxide Semiconductor ◽

Manufacturing Cost ◽

Effect Transistor ◽

The Impact

ABSTRACTRecently, we have experimentally demonstrated a very simply structured unipolar accumulation-type metal oxide semiconductor field effect transistor (AMOSFET) using grow-in-place silicon nanowires. The AMOSFET consists of a single doping type nanowire, metal source and drain contacts which are separated by a partially gated region. Despite its simple configuration, it is capable of high performance thereby offering the potential of a low manufacturing-cost transistor. Since the quality of the metal/semiconductor ohmic source and drain contacts impacts AMOSFET performance, we repot here on initial exploration of contact variations and of the impact of thermal process history. With process optimization, current on/off ratios of 106 and subthreshold swings of 70 mV/dec have been achieved with these simple devices

Download Full-text

Characterization of HfO2/Si Exposed to Water Vapor at Room Temperature

MRS Proceedings ◽

10.1557/proc-0917-e11-02 ◽

2006 ◽

Vol 917 ◽

Author(s):

Carlos Driemeier ◽

Elizandra Martinazzi ◽

Israel J. R. Baumvol ◽

Evgeni Gusev

Keyword(s):

Water Vapor ◽

Metal Oxide ◽

Room Temperature ◽

Gate Dielectric ◽

Metal Oxide Semiconductor ◽

Oxide Semiconductor ◽

Dielectric Films ◽

Nuclear Reaction Analysis ◽

Environmental Air

AbstractHfO2-based materials are the leading candidates to replace SiO2 as the gate dielectric in Si-based metal-oxide-semiconductor filed-effect transistors. The ubiquitous presence of water vapor in the environments to which the dielectric films are exposed (e.g. in environmental air) leads to questions about how water could affect the properties of the dielectric/Si structures. In order to investigate this topic, HfO2/SiO2/Si(001) thin film structures were exposed at room temperature to water vapor isotopically enriched in 2H and 18O followed by quantification and profiling of these nuclides by nuclear reaction analysis. We showed i) the formation of strongly bonded hydroxyls at the HfO2 surface; ii) room temperature migration of oxygen and water-derived oxygenous species through the HfO2 films, indicating that HfO2 is a weak diffusion barrier for these oxidizing species; iii) hydrogenous, water-derived species attachment to the SiO2 interlayer, resulting in detrimental hydrogenous defects therein. Consequences of these results to HfO2-based metal-oxide-semiconductor devices are discussed.

Download Full-text