Controlling the Structure and Photoproperties of SiV Diamond Nanoslab at Room Temperature by External Pressure for Optical Measurements of Temperature and Pressure

Abstract

External pressure is one of the key parameters to understand photoemission nanomaterials since the external pressure changes their photoproperties without introducing any chemical treatment. Here, we computationally elucidated the effects of the external pressure on structures, orbitals, photoproperties, and vibrational dynamics of a silicon vacancy (SiV) diamond nanoslab. We studied its attributes not only on the ground state at 0 K but also on the excited state around room temperature (RT) using an ab initio molecular dynamics simulation. We directly and mechanically pressed the SiV diamond nanoslab fluctuating around RT to mimic an actual external pressure usually generated in an anvil cell at RT. We found that the compression induces the shrunk SiV defect structures, the rearranged defect orbital energies, the switch of the optical transition from the SiV–SiV excitation to the nanoslab–SiV excitation, the hybridization of the SiV with nanoslab carbon (C) orbitals, and the blue shift and the smaller intensity of the spectra of the Si atom oscillation and the inner C–C bond vibration. The energies of absorption, emission, and zero-phonon line do not change monotonically but have the maxima below a 7%-compression. Especially, the absorption energy differs more between 0 K and RT as the compression increases, while the largest deviation between 0 K and RT in the emission energy appears below the 7%-compression. It is remarkable that all of these changes are caused only by the mechanical compression and that the compression differently pronounces the temperature effect. The obtained insights will provide a way to effectively control a split-vacancy center to be a promising single-photon source for nanoscale optical measurements of temperature and pressure in a compressed nanoscale material.