Parallelized Ab Initio Quantum Transport Simulation of Nanoscale Bismuthene Devices

We describe our parallel ab initio quantum transport solver implemented in C programming language, with bismuthene nanoribbon (BiNRs) simulations used for the demonstration of its performance. The inputs are Hamiltonians obtained from ab initio density functional theory (DFT), which are wannierized into a localized basis to increase Hamiltonian matrix sparsity and to reduce the computational load without the loss of bandstructure accuracy. Numerical matrix operations are parallelized for cluster computation and optimized using Intel Message Passing Interface (MPI) and Intel oneAPI Math Kernel Library (MKL). We demonstrate that an acceleration of about ~45× is achieved through parallelization on 64 Xeon Silver CPU cores compared to a single-core execution. Finally, we investigate the electronic, transport and device properties of ultra-scaled bismuthene nanodevices.

I. Introduction

In the last 60 years, semiconductor industry growth has been driven by transistor miniaturization and introduction of performance boosters such as metal gates, high-k dielectrics, and strain. The current state-of-the-art transistor technology is fin field-effect transistor (FinFET) with a nanoscale active region. Fabrication and device optimization at such scale are expensive and complex due to strong quantum mechanical effects which a strong impact on device performance. At ultra-short gate lengths, i.e. under ~20 nm, enabling short channel effects (SCEs) suppression is difficult and, hence, new materials and structures are sought to enable further device scaling and to improve device performance [1].