ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Experimental investigations are conducted in order to collect basic data for evaluating proton-exchanged LiTaO3 optical waveguides and their fabrication processes and systems using the line-focus-beam ultrasonic material characterization system, in the frequency range 100–300 MHz. Seven Z-cut LiTaO3 substrates are proton exchanged at several process temperatures (220–280 °C) and times (5–30 min) in a pyrophosphoric acid solution. Leaky surface acoustic wave (LSAW) velocities, measured for all specimens, decrease for all propagation directions. The decrease rate is at maximum in the Y-axis propagation direction, in which the measurement sensitivity to the process conditions is highest. The fH dependences of LSAW velocities, obtained from frequency dependences of LSAW velocities and proton-exchanged layer depths analyzed by secondary-ion mass spectrometry, have almost constant gradients of −0.78 (m/s)/(Hz m). Normalized depth distributions of the elastic properties of proton-exchanged layers are nearly equal; only the depths differ. Also, the relationships among LSAW velocities, layer depths, process times, process temperatures, and diffusion coefficients are experimentally obtained. Homogeneity evaluation of a proton-exchanged, 2-in., Z-cut LiTaO3 wafer processed at 260 °C for 14 min is demonstrated, resulting in a maximum LSAW velocity variation of 1.3 m/s. This corresponds to a depth variation of 7.4 nm and a temperature variation of 0.8 °C for the whole surface. © 2001 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1340008
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