Doping and temperature-dependent UV-Vis optical constants of cubic SrTiO₃: a combined spectroscopic ellipsometry and first-principles study

Abstract

SrTiO3 is the model perovskite compound and has demonstrated technological relevance from being the foundation of oxide electronics to a promising candidate as a high-temperature hydrogen sensor. Here, we fully investigate the temperature-dependent UV-Vis optical constants of pristine and doped SrTiO3 in the spectral range 0.73-5.90 eV using spectroscopic ellipsometry and first-principles. The oscillator model is applied to analyze and quantify the temperature and doping effect. After heating SrTiO3 from 300 to 873 K, the amplitude of the dominant absorption peak at 4.752 eV is reduced by 11% and the shoulder of optical spectrum at 3.708 eV gradually disappears. By doping SrTiO3 with Nb element from 0.05 to 0.7% wt, extra momentum is provided to enable indirect absorption and an unconventional Urbach tail is observed due to the increased crystalline disorder. Moreover, the first-principles calculations considering the many-body excitonic effect and phonon-assisted indirect absorption are performed, which help to determine the physics origin of absorption peaks and explain the temperature influence. This work sheds light on temperature and doping dependence of UV-Vis dielectric functions of cubic SrTiO3, aiming to elucidate the novel fundamental optical phenomena of SrTiO3-based heterostructures or devices.

Effect of Structural Morphology and Material Factors on Radiative Properties of Hybrid Perovskite/Nanoporous GaN Hierarchical Composite Structure

“…The angle-dependent reflection spectroscopy and pseudodielectric function of two porous GaN are measured with the RC2 ellipsometer. The SE’s working principle and high-temperature test process have been reported in previous studies. , …”

“…The SE's working principle and high-temperature test process have been reported in previous studies. 43,44…”

Electrically conductive [Fe4S4]-based organometallic polymers

“…rotation and ipping, at the lower temperatures. 47,48 The structural rigidity of 1 toward temperature was also conrmed by the VT diffuse-reectance infrared spectroscopy (DRIFTS) in the temperature range of 173 to 373 K (Fig. S17 †).…”

Manipulating the carrier concentration and phase transition via Nb content in SrTiO3

“…as STO) is a well known as one of the typical perovskite-like oxides with the general formula ABO 3 . The STO system has attracted considerable attentions not only for being a model transition-metal oxide system where fundamental physics has been extensively studied 1 – 3 , but also for its potential application in new device fabrications due to its tunable electronic, optical and transport properties 4 – 12 . Many interesting properties have been discovered in the STO system, for example: STO is a quantum paraelectric 13 as well as the first reported insulating oxide superconducting material 14 ; LaAlO 3 /SrTiO 3 heterointerface has two-dimensional electron gas with highly mobility of charge carriers 15 , 16 ; migration of oxygen vacancies occurs at BaTiO 3−δ /SrTiO 3 interface 17 ; ferromagnetic metallic phase and antiferromagnetic insulating phase occur in strained SrRuO 3 /SrTiO 3 superlattices 18 .…”