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内容記述 |
Silicon carbide (SiC) has the great potential for quantum sensing, and the several spin defect candidates have been reported. The negatively charged silicon vacancy (VSi-) is one promising candidate, and it has been recently demonstrated that the VSi- based magnetic sensors can operate above 591 K, while the magnetic sensitivity at 549 K is reduced by half compared to that at 300 K [2]. An alternative candidate for spin defects includes vanadium (V4+) in its neutral state in 4H-SiC, which exhibits photoluminescence (PL) at a wavelength of 1.3 μm within the optical telecom O-band (original band) [3 - 5]. Although spin-state manipulation of the V4+ state has been realized at low temperatures [4], there is a room for further discussion regarding the electronic structure of V4+ and its optical properties. Here, we performed a PL study of V-doped 4H-SiC epi-layers over a wide temperature range. The V-doped 4H-SiC epitaxial layer was grown in a CVD reactor using liquid VCl4 as the V dopant source [6]. A 50 μm-thick V-doped layer (V: 3 × 1013 - 6× 1015 cm-3) was grown on a commercial n+ SiC (0001) substrate. The PL spectra from 80 to 673 K were obtained with the use of a 976 nm laser as the excitation source. While the luminescence intensity monotonically declined with elevating temperature, luminescence was detected even at 673 K. The decay curve of V4+ luminescence was also obtained using a long-pass filter (> 1150 nm) or a band-pass filter (1300 ± 50 nm) over the same temperature range. The decay curves of the V4+ luminescence appears to consist of two components with the optical lifetimes in the range of 10 - 150 ns and ~ μs. In this report, the luminescence mechanism of V-doped 4H-SiC will be discussed based on PL studies towards infrared emitters operating at elevated temperatures. |
