Optical switching of defect charge states in 4H-SiC

Area of Science:

• Materials Science
• Quantum Computing
• Solid-State Physics

Background:

• Divacancy defects in silicon carbide (SiC) are crucial for quantum information applications.
• Understanding and controlling the charge states of these defects is essential for device stability and performance.

Purpose of the Study:

• To demonstrate optically induced switching between bright and dark charged divacancy defects in 4H-SiC.
• To identify the specific optical excitation conditions required for charge conversion.
• To explore the potential applications of this phenomenon in data storage and quantum memory.

Main Methods:

• Photoluminescence (PL) excitation spectroscopy.
• Time-resolved photoluminescence (TRPL) measurements.
• Optical manipulation using lasers at different energy levels (below and above 1.3 eV).

Main Results:

• Optically induced switching between bright (neutral) and dark (charged) divacancy states in 4H-SiC was achieved.
• Low-energy excitation (< 1.3 eV) suppressed PL by over two orders of magnitude, converting neutral divacancies (V_SiV_C⁰) to a dark state.
• A higher-energy repump laser (> 1.3 eV) rapidly recovered the bright PL state with a 30 μs time constant, indicating conversion back to the neutral state.
• Switching off the repump laser resulted in a bi-exponential decay of PL, with fast (100–200 μs) and slow (seconds) components.

Conclusions:

• The observed effects are attributed to the reversible conversion between two distinct charge states of divacancy defects in 4H-SiC.
• This optically controlled charge switching offers a pathway for manipulating defect properties.
• The phenomenon holds promise for developing novel long-term data storage solutions and nuclear-spin-based quantum memory devices.