An Investigation of Structural, Optical and Pyroelectrical Properties of LiTaO3

Abstract

In this study, structural, optical, and pyroelectric properties of Z-cut single crystal LiTaO3 bulk materials with thicknesses of 27 µm and 250 µm are analyzed. XRD results show characteristic diffraction peaks of Z-cut LiTaO3 at (012), (006), and (202), along with a Ta2O5 peak due to Li-deficiency. The strong (006) peak confirms a high c-orientation, indicating pyroelectric potential. Raman spectroscopy confirms agreement with known vibration modes of bulk LiTaO3. Band gap values for the 27 µm and 250 µm samples are determined as 4.44 eV and 4.65 eV, respectively, with both showing a direct band gap. Temperature changes from 30 ℃ to 180 ℃ were applied at rates of 50 ℃, 100 ℃, and 150 ℃. As temperatures rose, negative pyroelectric currents were observed; with cooling, currents shifted positive. The 250 µm thick, 24 mm² LiTaO3 wafer produced about 4 nA at 50 ℃ rate, rising to 12-13 nA at 150 ℃. With larger surface areas yielding higher currents, measurements on three wafers at a 50 ℃ change showed the highest-area sample producing ~7.5 nA, while the smallest yielded ~0.5 nA. The mean pyroelectric current density was higher in 27 µm (180 µA/m²) than in 250 µm (125 µA/m²), and the pyroelectric coefficient increased with decreasing thickness, measured at 33.43 µC/m²∙K (27 µm) and 23.22 µC/m²∙K (250 µm). These results suggest the potential of LiTaO3 crystals in IR detectors and self-powered deep UV detector applications due to their wide band gap.

Keywords

• LiTaO3
• Pyroelectric
• Pyrocurrent
• IR detector
• Pyroelectric material

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