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We investigated the effects of nitrogen doping in amorphous carbon layers on the diffusion of fluorine atoms based on density functional theory calculations. For N doping at both substitutional and interstitial sites, the F atom binds to the surrounding C atoms rather than the N atom during structural relaxation due to the electrostatic repulsion between N and F atoms. Furthermore, the diffusion barriers associated with the F atom passing by the N atom are extremely large (5.19 eV for substitutional N doping and 4.77 eV for interstitial N doping), primarily due to the electrostatic repulsion originating from the strong electronegativities of both atoms. The results clearly show that N doping increases the diffusion barrier of the F atom, thereby suppressing the diffusion of the F atom. The findings provide information about the role of N doping in amorphous carbon layers and yield insights for improving the fabrication processes of future integrated semiconductor devices. [ABSTRACT FROM AUTHOR]

The rapid and uniform growth of hydrogenated silicon (Si:H) films is essential for the manufacturing of future semiconductor devices; therefore, Si:H films are mainly deposited using SiH4-based plasmas. An increase in the pressure of the mixture gas has been demonstrated to increase the deposition rate in the SiH4-based plasmas. The fact that SiH4 more efficiently generates Si2H6 at higher gas pressures requires a theoretical investigation of the reactivity of Si2H6 on various surfaces. Therefore, we conducted first-principles density functional theory (DFT) calculations to understand the surface reactivity of Si2H6 on both hydrogenated (H-covered) Si(001) and Si(111) surfaces. The reactivity of Si2H6 molecules on hydrogenated Si surfaces was more energetically favorable than on clean Si surfaces. We also found that the hydrogenated Si(111) surface is the most efficient surface because the dissociation of Si2H6 on the hydrogenated Si(111) surface are thermodynamically and kinetically more favorable than those on the hydrogenated Si(001) surface. Finally, we simulated the SiH4/He capacitively coupled plasma (CCP) discharges for Si:H films deposition. [ABSTRACT FROM AUTHOR]

For the development of the future ultrahigh-scale integrated memory devices, a uniform tungsten (W) gate deposition process with good conformal film is essential for improving the conductivity of the W gate, resulting in the enhancement of device performance. As the memory devices are further scaled down, uniform W deposition becomes more difficult because of the experimental limitations of the sub-nanometer scale deposition even with atomic layer deposition (ALD) W processes. Even though it is known that the B 2 H 6 dosing process plays a key role in the deposition of the ALD W layer with low resistivity and in the removal of residual fluorine (F) atoms, the roles of H 2 and N 2 treatments used in the ALD W process have not yet been reported. To understand the detailed ALD W process, we have investigated the effects of H 2 and N 2 treatment on TiN surfaces for the B 2 H 6 dosing process using first-principles density functional theory (DFT) calculations. In our DFT calculated results, H 2 treatment on the TiN surfaces causes the surfaces to become H-covered TiN surfaces, which results in lowering the reactivity of the B 2 H 6 precursor since the overall reactions of the B 2 H 6 on the H-covered TiN surfaces are energetically less favorable than the TiN surfaces. As a result, an effect of the H 2 treatment is to decrease the reactivity of the B 2 H 6 molecule on the TiN surface. However, N 2 treatment on the Ti-terminated TiN (111) surface is more likely to make the TiN surface become an N-terminated TiN (111) surface, which results in making a lot of N-terminated TiN (111) surfaces, having a very reactive nature for B 2 H 6 bond dissociation. As a result, the effect of N 2 treatment serves as a catalyst to decompose B 2 H 6 . From the deep understanding of the effect of H 2 and N 2 during the B 2 H 6 dosing process, the use of proper gas treatment is required for the improvement of the W nucleation layers., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this paper, InAs 0.81 Sb 0.19 -based hetero-junction photovoltaic detector (HJPD) with an In 0.2 Al 0.8 Sb barrier layer was grown on GaAs substrates. By using technology computer aided design (TCAD), a design of a barrier layer that can achieve nearly zero valance band offsets was accomplished. A high quality InAs 0.81 Sb 0.19 epitaxial layer was obtained with relatively low threading dislocation density (TDD), calculated from a high-resolution X-ray diffraction (XRD) measurement. This layer showed a Hall mobility of 15,000 cm 2 /V⋅s, which is the highest mobility among InAsSb layers with an Sb composition of around 20% grown on GaAs substrates. Temperature dependence of dark current, photocurrent response and responsivity were measured and analyzed for fabricated HJPD. HJPD showed the clear photocurrent response having a long cutoff wavelength of 5.35 μm at room temperature. It was observed that the dark current of HJPDs is dominated by the diffusion limited current at temperatures ranging from 200K to room temperature from the dark current analysis. Peak responsivity of HJPDs exhibited the 1.18 A/W and 15 mA/W for 83K and a room temperature under zero bias condition even without anti-reflection coating (ARC). From these results, we believe that HJPDs could be an appropriate PD device for future compact and low power dissipation mid-infrared on-chip sensors and imaging devices.