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Scanning electron micrograph of a nanoporous InP (111) membrane. The inset gives a top view of the hexagonal arrangement of the pores.
Effect of rotating a magnetic field in the plane of the sample on the peak-to-peak terahertz field emitted. (a) A bulk InP sample without ion irradiation. (b) A nanoporous InP sample with Kr ion irradiation at a level of (circles) and the same sample, now rotated through an azimuthal angle of 60° (diamonds). (c) A nanoporous InP sample with Xe ion irradiation at a level of (circles) and the same sample, now rotated through an azimuthal angle of 60° (diamonds). The data illustrate that transient current effects are present in the bulk material but not in the irradiated nanoporous material.
Effect of varying the excitation pump fluence on the terahertz emission from (111) nanoporous InP ion-irradiated in four different ways. (a) Kr-irradiated samples. (b) Xe-irradiated samples. The terahertz emission in all cases is directly proportional to the pump power. There is no evidence for saturation in the relationship (as is often observed in the case of charge-carrier screening in transient-current emitters).
Azimuthal angle dependence of the terahertz emission from a Xe-irradiated nanoporous InP (111) membrane. The central 3 ps of the terahertz time-domain spectrum is plotted for each separate azimuthal angle, spaced at 5° intervals. (a) Magnitude of the horizontally polarized terahertz field, over one-third of a full rotation, or 120°. (b) Magnitude of the vertically polarized terahertz field, over one-third of a full rotation, or 120°. The same relative units for terahertz field are used in each panel.
Relative terahertz (THz) electric field amplitude from nine different InP (111) samples.
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