Előadó: Rohit Babar (Linköping University (host: Barcza Gergely))
Előadás: Spin centers in boron nitride and silicon carbide for quantum technology applications
Dátum: 2022. május 10., 10:00
Helyszín: 1-es épület Tanácsterem, https://wigner-hu.zoom.us/j/85242181421?pwd=MjFxTGNIR1ZFSHlXTlRaeWRhZVI… Meeting ID: 852 4218 1421 Passcode: 648715
Spin centers in wide-bandgap semiconductors have emerged as promising candidates for quantum communication, storage, and sensing applications. The spin centers typically comprise optically active intrinsic defects or dopant atoms in semiconducting host, with the feasibility of spin coherent, bright emission, and stable operation determined by the spin center-host interactions. The emergence of spin centers in two-dimensional host represents a new milestone in nanoscale sensing as the increased proximity to source could lead to high-resolution sensors. In this talk, I will present the first-principles study of novel spin centers in hexagonal boron nitride (hBN). We investigate the stability and magneto-optical properties of boron vacancy pair in the neutral charge state. This spin center is optically addressable with a long-lived memory, and can serve as a sensor with an efficient coherence protection scheme within a dense nuclear spin environment. Similarly, the tetramer carbon clusters in hBN are identified as potential spin centers with zero phonon line emission in the visible spectral range. Among bulk semiconductors, the mature growth and implantation techniques for silicon carbide (SiC) have led to controlled generation of spin centers. The negatively charged silicon vacancy in 4H-SiC is a widely reported spin center, however, the source of electron paramagnetic resonance and photoluminescence measurements close to the vacancy remains unknown. Based on our combined theory and experiment investigation, we attribute these signals to silicon vacancy perturbed by neighboring carbon antisite. Lastly, we demonstrate the modification of spin center properties in the presence of an extended defect. For the divacancy-stacking fault complex in 4H-SiC, the distinct divacancy configurations within the stacking fault show a large zero-field splitting. This could potentially lead to development of robust spin centers by further improving the coherence protection scheme achieved for basal divacancies in 4H-SiC.