H. Mertens | Searcharxiv

arXiv2023

Dual Operation of Gate-All-Around Silicon Nanowires at Cryogenic Temperatures: FET and Quantum Dot

As CMOS structures are envisioned to host silicon spin qubits, and for co-integrating quantum systems with their classical control blocks, the cryogenic behaviour of such structures need to be investigated. In this paper we characterize the electrical properties of Gate-All-Around (GAA) n-MOSFETs Si nanowires (NWs) from room temperature down to 1.7 K. We demonstrate that those devices can operate both as transistor and host quantum dots at cryogenic temperature. In the classical regime of the transistor we show improved performances of the devices and in the quantum regime we show systematic quantum dots formation in GAA devices.

cond-mat.mes-hall↗

arXiv2007

Strong luminescence quantum efficiency enhancement near prolate metal nanoparticles: dipolar versus higher-order modes

We present a theoretical study of the radiative and nonradiative decay rates of an optical emitter in close proximity to a prolate-shaped metal nanoparticle. We use the model developed by Gersten and Nitzan, that we correct for radiative reaction and dynamic depolarization and extend for prolate particle shapes. We show that prolate-shaped metal nanoparticles can lead to much higher quantum efficiency enhancements than corresponding spherical nanoparticles. For properly engineered emitter-nanoparticle geometries, quantum efficiency enhancements from an initial value of 1% (in absence of the nanoparticle) to 70% are feasible. We describe the anisotropy-induced enhancement effects in terms of large field enhancements near the metal tips that cause strong coupling to the (radiative) dipolar modes. For increasing particle anisotropy, a strong spectral separation between radiative dipolar and dark higher-order modes occurs, which leads to higher radiative efficiencies for anisotropic particles. In addition, we demonstrate that for large (> 100 nm) nanoparticles, the influence of Ohmic losses on plasmon-enhanced luminescence is substantially reduced, which implies that, if prolate shaped, even lossy metals such as Al and Cu are suitable materials for optical nano-antennas.

cond-mat.other↗