Germanium oxynitride gate dielectrics formed by plasma nitridation of ultrathin thermal oxides on Ge(100)

Kutsuki, Katsuhiro; Okamoto, Gaku; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji

doi:10.1063/1.3171938

Cited by 58 publications

(44 citation statements)

References 14 publications

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“…This will enable future studies to assess ALD of Al 2 O 3 , as well as other feasible high-ĸ candidates and passivation strategies (such as hafnia, zirconia, tantalum, germanium oxynitride [96][97][98][99][100] and bi/tri-layer dielectrics [101][102][103][104] ) on pristine and oxidised Ge surfaces. As such, ReaxFF can be instrumental in identifying optimal processing conditions to form high quality high-ĸ dielectrics/non-Si semiconductor interfaces.…”

Section: Applications Of Reaxffmentioning

confidence: 99%

The ReaxFF reactive force-field: development, applications and future directions

et al. 2016

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The reactive force-field (ReaxFF) interatomic potential is a powerful computational tool for exploring, developing and optimizing material properties. Methods based on the principles of quantum mechanics (QM), while offering valuable theoretical guidance at the electronic level, are often too computationally intense for simulations that consider the full dynamic evolution of a system. Alternatively, empirical interatomic potentials that are based on classical principles require significantly fewer computational resources, which enables simulations to better describe dynamic processes over longer timeframes and on larger scales. Such methods, however, typically require a predefined connectivity between atoms, precluding simulations that involve reactive events. The ReaxFF method was developed to help bridge this gap. Approaching the gap from the classical side, ReaxFF casts the empirical interatomic potential within a bond-order formalism, thus implicitly describing chemical bonding without expensive QM calculations. This article provides an overview of the development, application, and future directions of the ReaxFF method. INTRODUCTIONAtomistic-scale computational techniques provide a powerful means for exploring, developing and optimizing promising properties of novel materials. Simulation methods based on quantum mechanics (QM) have grown in popularity over recent decades due to the development of user-friendly software packages making QM level calculations widely accessible. Such availability has proved particularly relevant to material design, where QM frequently serves as a theoretical guide and screening tool. Unfortunately, the computational cost inherent to QM level calculations severely limits simulation scales. This limitation often excludes QM methods from considering the dynamic evolution of a system, thus hampering our theoretical understanding of key factors affecting the overall behaviour of a material. To alleviate this issue, QM structure and energy data are used to train empirical force fields that require significantly fewer computational resources, thereby enabling simulations to better describe dynamic processes. Such empirical methods, including reactive force-field (ReaxFF), 1 trade accuracy for lower computational expense, making it possible to reach simulation scales that are orders of magnitude beyond what is tractable for QM.Atomistic force-field methods utilise empirically determined interatomic potentials to calculate system energy as a function of atomic positions. Classical approximations are well suited for nonreactive interactions, such as angle-strain represented by harmonic potentials, dispersion represented by van der Waals potentials and Coulombic interactions represented by various polarisation schemes. However, such descriptions are inadequate for modelling changes in atom connectivity (i.e., for modelling chemical reactions as bonds break and form). This motivates the

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Section: Applications Of Reaxffmentioning

confidence: 99%

The ReaxFF reactive force-field: development, applications and future directions

et al. 2016

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“…One approach is to use thermal or plasma techniques such as nitridation to passivate a GeO 2 surface by forming a GeON layer on top of GeO 2 . 7 Another approach is to cap the GeO 2 surface by the deposition of high-k dielectric layers. 8,9 Metal-oxide-doped GeO 2 such as yttrium-GeO 2 has attracted interest because of its stronger resistance to liquid water than pure GeO 2 .…”

Section: Introductionmentioning

confidence: 99%

Comparative study of GeO2/Ge and SiO2/Si structures on anomalous charging of oxide films upon water adsorption revealed by ambient-pressure X-ray photoelectron spectroscopy

Mori

Oka

Hosoi

et al. 2016

Journal of Applied Physics

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The energy difference between the oxide and bulk peaks in X-ray photoelectron spectroscopy (XPS) spectra was investigated for both GeO 2 /Ge and SiO 2 /Si structures with thickness-controlled water films. This was achieved by obtaining XPS spectra at various values of relative humidity (RH) of up to $15%. The increase in the energy shift is more significant for thermal GeO 2 on Ge than for thermal SiO 2 on Si above $10 À4 % RH, which is due to the larger amount of water molecules that infiltrate into the GeO 2 film to form hydroxyls. Analyzing the origins of this energy shift, we propose that the positive charging of a partially hydroxylated GeO 2 film, which is unrelated to X-ray irradiation, causes the larger energy shift for GeO 2 /Ge than for SiO 2 /Si. A possible microscopic mechanism of this intrinsic positive charging is the emission of electrons from adsorbed water species in the suboxide layer of the GeO 2 film to the Ge bulk, leaving immobile cations or positively charged states in the oxide. This may be related to the reported negative shift of flat band voltages in metaloxide-semiconductor diodes with an air-exposed GeO 2 layer. Published by AIP Publishing.

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“…As conventional energy sources such as coal, oil, and natural gas are exhausted, solar energy is becoming increasingly crucial [1][2][3][4][5][6][7][8][9][10][11][12][13]. The combustion of fossil fuels produces carbon dioxide, which causes the greenhouse effect.…”

Section: Introductionmentioning

confidence: 99%

Silicon Heterojunction Solar Cells Using AlOx and Plasma-Immersion Ion Implantation

Lin

You

et al. 2014

Energies

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Aluminum oxide (AlO x ) and plasma immersion ion implantation (PIII) were studied in relation to passivated silicon heterojunction solar cells. When aluminum oxide (AlO x ) was deposited on the surface of a wafer; the electric field near the surface of wafer was enhanced; and the mobility of the carrier was improved; thus reducing carrier traps associated with dangling bonds. Using PIII enabled implanting nitrogen into the device to reduce dangling bonds and achieve the desired passivation effect. Depositing AlO x on the surface of a solar cell increased the short-circuit current density (J sc ); open-circuit voltage (V oc ); and conversion efficiency from 27.84 mA/cm 2 ; 0.52 V; and 8.97% to 29.34 mA/cm 2 ; 0.54 V; and 9.68%; respectively. After controlling the depth and concentration of nitrogen by modulating the PIII energy; the ideal PIII condition was determined to be 2 keV and 10 min. As a result; a 15.42% conversion efficiency was thus achieved; and the J sc ; V oc ; and fill factor were 37.78 mA/cm 2 ; 0.55 V; and 0.742; respectively.

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Germanium oxynitride gate dielectrics formed by plasma nitridation of ultrathin thermal oxides on Ge(100)

Cited by 58 publications

References 14 publications

The ReaxFF reactive force-field: development, applications and future directions

The ReaxFF reactive force-field: development, applications and future directions

Comparative study of GeO2/Ge and SiO2/Si structures on anomalous charging of oxide films upon water adsorption revealed by ambient-pressure X-ray photoelectron spectroscopy

Silicon Heterojunction Solar Cells Using AlOx and Plasma-Immersion Ion Implantation

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