Abstract
We demonstrate optically induced switching between bright and dark charged divacancy defects in 4H-SiC. Photoluminescence excitation and time-resolved photoluminescence measurements reveal the excitation conditions for such charge conversion. For an energy below 1.3 eV (above 950 nm), the PL is suppressed by more than two orders of magnitude. The PL is recovered in the presence of a higher energy repump laser with a time-averaged intensity less than 0.1% that of the excitation field. Under a repump of 2.33 eV (532 nm), the PL increases rapidly, with a time constant 30 μs. By contrast, when the repump is switched off, the PL decreases first within 100–200 μs, followed by a much slower decay of a few seconds. We attribute these effect to the conversion between two different charge states. Under an excitation at energy levels below 1.3 eV, VSiVC0 are converted into a dark charge state. A repump laser with an energy above 1.3 eV can excite this charged state and recover the bright neutral state. This optically induced charge switching can lead to charge-state fluctuations but can be exploited for long-term data storage or nuclear-spin-based quantum memory.
Highlights
Active point defects in wide-band-gap semiconductors can possess long electron spin coherence times (>1 ms) and have been considered for use in solid-state quantum sensing and information processing
We focus on the 4H–silicon carbide (SiC) polytype, in which the two adjacent carbon and silicon vacancies of VSiVC0 organize in either axial or basal configurations as a result of varying lattice sites and orientations
We identify the optimal pump laser energy by using photoluminescence excitation (PLE) measurements
Summary
Active point defects (color centers) in wide-band-gap semiconductors can possess long electron spin coherence times (>1 ms) and have been considered for use in solid-state quantum sensing and information processing. Similar defects have been identified in silicon carbide (SiC) for use in wafer-scale quantum technologies[1]. SiC crystals form in three main polytypes – 4H, 6H (hexagonal), and 3C (cubic) – offering a broad range of defects[2] that can act as potential spin qubits, among which are the carbon antisite-vacancy pair (CSiVC)[3,4,5,6], the nitrogen vacancy (NCVSi)[7,8,9], the silicon monovacancy VSi−10–13, and the neutral divacancy (VSiVC0)[14,15,16]
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