The impacts of electronic state hybridization on the binding energy of single phosphorus donor electrons in extremely downscaled silicon nanostructures

Abstract

Articles you may be interested inThe electric field effects on the binding energies and the nonlinear optical properties of a donor impurity in a spherical quantum dot J. Appl. Phys. 109, 094309 (2011); 10.1063/1.3582137 Effect of polarization and self-energy on the ground donor state in the presence of conduction band nonparabolicity in GaAs-(Al,Ga)As spherical quantum dotThe effect of a spatially dependent effective mass on hydrogenic impurity binding energy in a finite parabolic quantum well with a magnetic field Towards an accurate gold carbonyl binding energy in AuCO + : Basis set convergence and a comparison between density functional and conventional methodsWe present the density functional theory calculations of the binding energy of the Phosphorus (P) donor electrons in extremely downscaled single P-doped Silicon (Si) nanorods. In past studies, the binding energy of donor electrons was evaluated for the Si nanostructures as the difference between the ionization energy for the single P-doped Si nanostructures and the electron affinity for the undoped Si nanostructures. This definition does not take into account the strong interaction of donor electron states and Si electron states explicitly at the conductive states and results in a monotonous increase in the binding energy by reducing the nanostructure's dimensions. In this paper, we introduce a new approach to evaluate the binding energy of donor electrons by combining the projected density of states (PDOS) analysis and three-dimensional analysis of associated electron wavefunctions. This enables us to clarify a gradual change of the spatial distribution of the 3D electron wavefunctions (3DWFs) from the donor electron ground state, which is fully localized around the P donor site to the first conductive state, which spreads over the outer Si nanorods contributing to current conduction. We found that the energy of the first conductive state is capped near the top of the atomistic effective potential at the donor site with respect to the surrounding Si atoms in nanorods smaller than about 27 a 0 . This results in the binding energy of approximately 1.5 eV, which is virtually independent on the nanorod's dimensions. This fact signifies a good tolerance of the binding energy, which governs the operating temperature of the single dopant-based transistors in practice. We also conducted the computationally heavy transmission calculations of the single P-doped Si nanorods connected to the source and drain electrodes. The calculated transmission spectra are discussed in comparison with the atomistic effective potential distributions and the PDOS-3DWFs method. V C 2014 AIP Publishing LLC. [http://dx.

Electron transport via a few-dopant cluster in the presence of counter-dopants in silicon nanowire transistors

“…The Fermi level (E F ) is set as 0 eV for all simulations and the gate voltage (V G ) is kept as 0 V. From the comparison of the undoped and single-P-doped cases, extra energy states below the conduction band edge can be identified when the P-donor is introduced in the channel, although they are known to be strongly hybridized with the Si energy states. 26) These states are expected to contribute to current at lower V G values, which can be probed by the I D -V G characteristics. Figure 2(c) shows these I D -V G characteristics simulated for T = 300 K and V D = 5 mV (small source-drain bias window, comparable to experimental setups 15) ).…”