Abstract

This study examines the temperature-dependent screening effect on the phonon-drag-induced Seebeck coefficient (Sg) in a bilayer graphene (BLG)-AlGaAs/quasi-two-dimensional electron gas (q2DEG) system. The BLG layer interacts with both deformation potential acoustic phonons and stronger piezoelectric field acoustic phonons from AlGaAs/GaAs. We compare the electron–phonon interactions in BLG with and without screening by q2DEG. The screening effect reduces Sg, particularly at low temperatures, and shows a strong dependence on the carrier density in the BLG layer. The double-layer screening function increases Sg with layer separation (d), paralleling the monolayer screening at large d. Additionally, varying the GaAs quantum well width (L) reveals that Sg increases with L < 100 Å under double-layer screening but remains unchanged beyond this threshold, while monolayer screening decreases Sg as L increases. Both screening functions enhance Sg when the BLG carrier density is lower than that of q2DEG, though the magnitude difference between them is minimal.

Abstract

This study examines the temperature-dependent screening effect on the phonon-drag-induced Seebeck coefficient (Sg) in a bilayer graphene (BLG)-AlGaAs/quasi-two-dimensional electron gas (q2DEG) system. The BLG layer interacts with both deformation potential acoustic phonons and stronger piezoelectric field acoustic phonons from AlGaAs/GaAs. We compare the electron–phonon interactions in BLG with and without screening by q2DEG. The screening effect reduces Sg, particularly at low temperatures, and shows a strong dependence on the carrier density in the BLG layer. The double-layer screening function increases Sg with layer separation (d), paralleling the monolayer screening at large d. Additionally, varying the GaAs quantum well width (L) reveals that Sg increases with L < 100 Å under double-layer screening but remains unchanged beyond this threshold, while monolayer screening decreases Sg as L increases. Both screening functions enhance Sg when the BLG carrier density is lower than that of q2DEG, though the magnitude difference between them is minimal.

Abstract

This study examines the temperature-dependent screening effect on the phonon-drag-induced Seebeck coefficient (Sg) in a bilayer graphene (BLG)-AlGaAs/quasi-two-dimensional electron gas (q2DEG) system. The BLG layer interacts with both deformation potential acoustic phonons and stronger piezoelectric field acoustic phonons from AlGaAs/GaAs. We compare the electron–phonon interactions in BLG with and without screening by q2DEG. The screening effect reduces Sg, particularly at low temperatures, and shows a strong dependence on the carrier density in the BLG layer. The double-layer screening function increases Sg with layer separation (d), paralleling the monolayer screening at large d. Additionally, varying the GaAs quantum well width (L) reveals that Sg increases with L < 100 Å under double-layer screening but remains unchanged beyond this threshold, while monolayer screening decreases Sg as L increases. Both screening functions enhance Sg when the BLG carrier density is lower than that of q2DEG, though the magnitude difference between them is minimal.

Abstract

This study examines the temperature-dependent screening effect on the phonon-drag-induced Seebeck coefficient (Sg) in a bilayer graphene (BLG)-AlGaAs/quasi-two-dimensional electron gas (q2DEG) system. The BLG layer interacts with both deformation potential acoustic phonons and stronger piezoelectric field acoustic phonons from AlGaAs/GaAs. We compare the electron–phonon interactions in BLG with and without screening by q2DEG. The screening effect reduces Sg, particularly at low temperatures, and shows a strong dependence on the carrier density in the BLG layer. The double-layer screening function increases Sg with layer separation (d), paralleling the monolayer screening at large d. Additionally, varying the GaAs quantum well width (L) reveals that Sg increases with L < 100 Å under double-layer screening but remains unchanged beyond this threshold, while monolayer screening decreases Sg as L increases. Both screening functions enhance Sg when the BLG carrier density is lower than that of q2DEG, though the magnitude difference between them is minimal.