Intrinsic defects of GaSe

Area of Science:

• Materials Science
• Condensed Matter Physics
• Semiconductor Physics

Background:

• Gallium selenide (GaSe) is a layered semiconductor with tunable optical band gaps.
• Its potential in microelectronics, optoelectronics, and photovoltaics necessitates understanding intrinsic defects.
• Intrinsic defects significantly influence semiconductor device performance.

Purpose of the Study:

• To comprehensively investigate intrinsic point defects in both bulk and monolayer (ML) GaSe.
• To determine formation energies and charge transition levels of these defects.
• To understand how defect physics differs between bulk and monolayer GaSe.

Main Methods:

• Utilized an optimized hybrid functional for accurate electronic structure calculations.
• Calculated defect formation energies under quasi-equilibrium conditions.
• Determined charge transition levels and compared them with experimental data.

Main Results:

• Identified the interlayer gallium interstitial as the sole intrinsic donor in bulk GaSe; absent in ML GaSe.
• Found vacancies act as acceptors, and selenium interstitials are electrically inactive.
• Demonstrated that bulk GaSe is intrinsically well-compensated, making it an ideal substrate.
• Revealed monolayer GaSe is intrinsically p-type and cannot be compensated by intrinsic defects.

Conclusions:

• Intrinsic defects play a crucial role in the electronic properties of GaSe.
• Bulk GaSe exhibits compensated behavior due to intrinsic defects, suitable for substrates.
• Monolayer GaSe displays intrinsic p-type conductivity, with defect physics significantly altered by the reduced dimensionality and widened band gap.