Time-Dependent Transport in Low-Dimensional Systems—A Numerical Solution Using the Nonequilibrium Green's Functions

In this paper, we present a novel numerical solution to analyze time-dependent transport in low-dimensional systems, such as one-dimensional (1-D) quantum dot and quasi-one-dimensional (Q1D) carbon nanotube systems, by using the nonequilibrium Green's functions (NEGF). The novelty of proposed approach is to jointly handle the NEGF in both the time-domain and the real-space-domain in a recursive fashion. The time-domain recursive approach is a straightforward approach to solve time-dependent transport problems, while the real-space recursive approach makes the calculations feasible for arbitrary-length 1-D and Q1D systems. To verify our proposed algorithm, we apply this method to explore the transient and ac transport properties of a sample 1-D quantum-dot array system. We will present in this paper the simulated electrical current curves, J (t), in response to various pulses and sinusoid waveforms. From these simulation results, we can obtain the delay and distortion information. We will then discuss how the length of a quantum-dot array and the hopping energy affect the transport behavior. The knowledge we gain from this project will help researchers to evaluate the electrical properties of 1-D and Q1D materials. The knowledge can also benefit the making of time-dependent 1-D and Q1D nanoelectronic devices