No abstract

A method is presented for quantum-mechanical ballistic transport calculations of realistic two-and threedimensional open devices that may have any shape and any number of leads. Observables of the open system can be calculated with an effort comparable to a single calculation of a suitably defined closed system. The method is based on a previously developed scheme for calculating transmission functions, the contact block reduction method, and is shown to be applicable to the density matrix, the density of states, and the local carrier density. The electronic system may be characterized by a single or multiband Hamiltonian. We illustrate the method for the four-band GaAs hole transport through a two-dimensional three-terminal T-junction device and for the electron tunneling through a three-dimensional InAs quantum dot molecule embedded into an InP heterostructure.

nextnano is a simulation tool that aims at providing global insight into the basic physical properties of realistic three-dimensional mesoscopic semiconductor structures. It focuses on quantum mechanical properties such as the global electronic structure, optical properties, and the effects of electric and magnetic fields for virtually any geometry and combination of semiconducting materials. For the calculation of carrier dynamics, two models are currently implemented that provide results for the limiting cases of highly diffusive or purely ballistic quantum-mechanical transport. In this paper, we present an overview of nextnano's present and future capabilities and discuss some key concepts in the areas of code structure, numerical techniques, and electronic structure principles.

nextnano3 is a simulation tool that aims at providing global insight into the basic physical properties of realistic three-dimensional mesoscopic semiconductor structures. It focuses on quantum mechanical properties such as the global electronic structure, optical properties, and the effects of electric and magnetic fields for virtually any geometry and combination of semiconducting materials. For the calculation of the carrier dynamics a drift--diffusion model based on a quantum-mechanically calculated density is employed. In this paper we present an overview of the capabilities of nextnano 3 and discuss some of the main equations that are implemented into the code. As examples, we first discuss the strain tensor components and the piezoelectric effect associated with a compressively strained InAs layer for different growth directions, secondly, we calculate self-consistently the quantum mechanical electron density of a Double Gate MOSFET, then we compare the intersubband transitions in a multi-quantum well structure that have been obtained with a single-band effective mass approach and with an 8-band k · p model, and finally, we calculate the energy spectrum of a structure in a uniform magnetic field.