Enhancement of optical properties of boron-doped SiC thin film: a SiC QD effect
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Bull Mater Sci (2020)43:250 https://doi.org/10.1007/s12034-020-02212-5
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Enhancement of optical properties of boron-doped SiC thin film: a SiC QD effect KUSUMITA KUNDU1,2, JOY CHAKRABORTY3, SURESH KUMAR3, N ESHWARA PRASAD3 and RAJAT BANERJEE1,2,* 1
CSIR - Central Glass and Ceramic Research Institute, Jadavpur, Kolkata 700032, India Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India 3 Defence Materials and Stores Research and Development Establishment, Kanpur 208013, India *Author for correspondence ([email protected]) 2
MS received 15 November 2019; accepted 31 March 2020 Abstract. Silicon carbide quantum dots (SiC-QD) embedded inside the SiC thin film deposited on silicon (111) wafer is directly synthesized by modified chemical vapour deposition technique using boron-doped liquid polycarbosilane as a precursor. Subsequent microscopic characterization of the thin film exhibits the presence of QD, which is theoretically corroborated from the exciton Bohr radius. The film shows interesting visible and near-infra-red photoluminescence at room temperature with enhanced lifetime. In addition to the lifetime, the quantum efficiency in the visible emission was also enhanced substantially than what was reported previously. Keywords.
1.
3C-silicon carbide; thin film; SiC nanocrystals; quantum confinement effect.
Introduction
Researchers around the world have taken great interest in the structure-property correlation of silicon carbide (SiC) due to its semiconducting behaviour having a band gap from 2.3 to 3.3 eV which has a wide range of applications in electronic and optical industries [1–4]. Extensive research is carried out on SiC thin film coating on silicon to ascertain the protective criteria of this film under harsh environment [5]. This type of thin, hard coating deposited on silicon using different techniques [6], is the need of the hour considering its applications in micro-electromechanical systems environment wherein a catastrophic mechanical failure can cause extensive damage to the machine. Different coating procedures have been studied using different materials, polymers being one of them. Yajima et al [7] pioneered the process of the formation of continuous SiC fibres from polycarbosilane (PCS). Recently, researchers have focussed on the same polymeric material to derive SiC thin coating on a substrate so that it can be used as an effective optical material. In depth research on bulk SiC exhibits weak blue photoluminescence (PL) having a low quantum efficiency of 10-4 due to its indirect band gap [8,9]. Previously, SiC was considered to be a material for LED fabrication but due to weak quantum efficiency it was never considered seriously for optical applications. But if this polymer can
be tailor-made so that its conversion to SiC thin film can achieve appreciable enhancement of PL efficiency, it will be a step forward to the fabrication of high-performance LED. Fuchs et al [10] reported earlier that PL spectra g
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