Photoionization and far infrared absorption of single-electron transistors: Theoretical results and experiment proposals

Abstract

We present theoretical results demonstrating that photoionization and far infrared absorption can be valuable tools to investigate single-electron transistors (SETs), and encourage experimentalists to use them to study nanoelectronic devices. Photoionization permits to obtain information on how many electrons occupy a quantum dot and the charging energy in a direct manner. This is very important, because experiments carried out up to now, which measure the electric conductance, only allow to determine these quantities indirectly. It is worth emphasizing that in the photoionization processes considered by us, an electron absorbs a photon with energy of the order of the work functions (typically, ∼ 1 eV) and is ejected into the vacuum. This phenomenon is completely different from the widely studied photo-assisted tunneling considered by previous investigators, involving much lower photon energies ∼ 1 meV). We give concrete suggestions on how to conduct experiments using photoionization alone or in combination with transport measurements. Monitoring zero kinetic energy (ZEKE) photoelectrons is especially advisable in view of the high-resolution of the ZEKE-spectroscopy. We also suggest that far infrared absorption can be an even simpler method that photoionization to investigate SETs. © 2010 The Surface Science Society of Japan.