高圧ひずみ加工によるGaAsの熱伝導率の低減

抄録

We report a dramatic and irreversible reduction in the lattice thermal conductivity of bulk-crystalline Gallium Arsenide (GaAs) when subjected to intense plastic strain under a pressure of 24 GPa using high-pressure torsion (HPT). Thermal conductivity measurements show that the HPT-processed samples have a lattice thermal conductivity reduction by a factor of approximately 6 (from intrinsic single crystalline value of 42 Wm^-1 K^-1 to approximately 7 Wm^-1 K^-1). Thermal conductivity reduction in HPT-processed GaAs is attributed to the formation of nanograin boundaries and metastable phases which act as phonon scattering sites, and because of a large density of lattice defects introduced by HPT processing. Annealing the samples at 873 K increases the thermal conductivity due to the reduction in the density of secondary phases and lattice defects.