SrTiO3 (STO) thin films of different thicknesses were deposited on MgAl2O4 (MAO) substrates to investigate the in-plane strain effect on the soft-mode frequency of the STO films. X-ray reciprocal space mapping (X-RSM)...SrTiO3 (STO) thin films of different thicknesses were deposited on MgAl2O4 (MAO) substrates to investigate the in-plane strain effect on the soft-mode frequency of the STO films. X-ray reciprocal space mapping (X-RSM) results indicate that there was no relaxation of the in-plane lattice strain of the STO films on MAO. Shifts in the soft-mode frequencies with a decrease in the film thickness were observed using terahertz time-domain spectroscopy (THz-TDS). However, despite the larger lattice mismatch between STO and MAO than that between STO and DyScO3 (DSO), the shifts in the soft-mode frequencies of the STO films on MAO were smaller than those on DSO. The results indicate that the soft-mode frequencies of the STO films on MAO are affected by the c-axis (out-of-plane) lengths.展开更多
We propose dynamic terahertz(THz) emission microscopy(DTEM) to visualize temporal–spatial dynamics of photoexcited carriers in electronic materials. DTEM utilizes THz pulses emitted from a sample by probe pulses irra...We propose dynamic terahertz(THz) emission microscopy(DTEM) to visualize temporal–spatial dynamics of photoexcited carriers in electronic materials. DTEM utilizes THz pulses emitted from a sample by probe pulses irradiated after pump pulse irradiation to perform time-resolved two-dimensional mapping of the THz pulse emission, reflecting various carrier dynamics. Using this microscopy, we investigated carrier dynamics in the gap region of low-temperature-grown Ga As and semi-insulating Ga As photoconductive switches of the identical-dipole type. The observed DTEM images are well explained by the change in the electric potential distribution between the electrodes caused by the screening effect of the photoexcited electron-hole pairs.展开更多
文摘SrTiO3 (STO) thin films of different thicknesses were deposited on MgAl2O4 (MAO) substrates to investigate the in-plane strain effect on the soft-mode frequency of the STO films. X-ray reciprocal space mapping (X-RSM) results indicate that there was no relaxation of the in-plane lattice strain of the STO films on MAO. Shifts in the soft-mode frequencies with a decrease in the film thickness were observed using terahertz time-domain spectroscopy (THz-TDS). However, despite the larger lattice mismatch between STO and MAO than that between STO and DyScO3 (DSO), the shifts in the soft-mode frequencies of the STO films on MAO were smaller than those on DSO. The results indicate that the soft-mode frequencies of the STO films on MAO are affected by the c-axis (out-of-plane) lengths.
文摘We propose dynamic terahertz(THz) emission microscopy(DTEM) to visualize temporal–spatial dynamics of photoexcited carriers in electronic materials. DTEM utilizes THz pulses emitted from a sample by probe pulses irradiated after pump pulse irradiation to perform time-resolved two-dimensional mapping of the THz pulse emission, reflecting various carrier dynamics. Using this microscopy, we investigated carrier dynamics in the gap region of low-temperature-grown Ga As and semi-insulating Ga As photoconductive switches of the identical-dipole type. The observed DTEM images are well explained by the change in the electric potential distribution between the electrodes caused by the screening effect of the photoexcited electron-hole pairs.
