Solid-state spin color center is an important research platform for quantum information processing, and diamond nitrogen vacancy (NV) color center is its outstanding representative. Since the detection of a single diamond NV color center at room temperature was reported by a German research team in 1997, important progress has been made in quantum computing, quantum networking, and quantum sensing. In recent years, attention has been paid to similar color centers in other semiconductor materials in order to take advantage of more mature material processing technologies and device integration processes. The spin color centers in silicon carbide (SiC), including silicon vacancy (Vsi) color centers (missing one silicon atom) and double vacancy color centers (missing one silicon atom and one neighboring carbon atom), have attracted wide interest because of their excellent optical and spin properties.
SiC material with excellent properties such as wide band gap, high thermal conductivity, high carrier mobility, high breakdown voltage and high chemical stability is one of the important materials for high-power and high-temperature electronic devices. In the ground state, the silicon vacancy of SiC crystal exhibits C3v symmetry in 4H-SiC, a high spintronic state and emits light in the near infrared range of about 1.4 eV, which has attracted much attention. Vacancy is the most important point defect in SiC crystal, which is an intrinsic or natural defect, that is, dislocation atoms generally enter other vacancies or gradually migrate to the grain boundary or surface as shown in Fig. 1. Such vacancies are called Schottky vacancies. The Vsi defects of SiC wafer material provided by PAM-XIAMEN are much smaller than E15/cm3. Because of the high purity, there is not a silicon vacancy color center in a wide range scanned, such as 100*100*2um, even in 200*200*2um.
Silicon Vacancy Schematic
1. Negatively Charged Silicon Vacancies in Silicon Carbide
Single crystal SiC is a promising material for spin defect based quantum sensors because of its commercial availability and mature electrical and optical microfabrication device integration technologies. The negatively charged silicon vacancy (i.e. single missing silicon atoms with additional electrons at vacancy positions) is one of the main spin defects in silicon carbide research because of its near-telecom photoemission, high spin number and ground state zero-field splitting almost independent of temperature.
Negatively charged silicon vacancies have been observed in SiC crystal. Its electronic configuration is modeled by five active electrons (three holes), forming a unique spin 32 system, which makes possible the realization of new sensing protocols and spin quantum dots. In a single isolated defect, a spin coherence time of 0.8 ms was measured at 4 K. In the VSi ensemble, spin coherence time is observed dynamic decoupling techniques, which is up to T2 = 20 ms.
2. Methods for Producing Vsi in SiC Wafer
Many methods for producing VSi have been investigated, including irradiation using electrons, neutrons and protons. Furthermore, researchers have successfully developed ion implantation technology to prepare silicon carbide defect color centers in recent years. Photoelectron paramagnetic resonance (EPR) studies have shown that effective electron spin polarization can lead to silicon vacancies in silicon carbide, and its photoluminescence (PL) signal can be detected even at room temperature.
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