Title :
Growth of 4-inch diameter Li2B4O7 single crystals for SAW devices
Author :
Tsutsui, Noriaki ; Ino, Yusaku ; Imai, Koji ; Senguttuvan, Nachimuthu ; Ishii, M.
Author_Institution :
Chichibu Fuji Co. Ltd., Ogano, Japan
Abstract :
We report crystal growth of 4-inch diameter and 8-inch long lithium tetraborate (Li2B4O7) single crystals for SAW device applications. The crystals were grown by modified Bridgman method along <110> direction using platinum inserted carbon crucible under nitrogen atmosphere. The seed crystals were of same diameter (108 mm) to that of the crystals grown and of 25 mm in length. The crystals were grown at a rate of up to 0.5 mm/h. Wafers were cut at different places along the length of the ingot for studying the dislocation density distribution by chemical etching and X-ray topography. The EPD at center of wafer was found to be higher (1000 cm2) than at outer area (100 cm2). The SAW velocity has been measured across a 3-inch wafer and it was found that the variation of the velocity at different parts of the wafer was within ±0.04%
Keywords :
X-ray topography; crystal growth from melt; dislocation density; dislocation etching; lithium compounds; piezoelectric materials; surface acoustic wave devices; 4 inch; Li2B4O7; SAW device; SAW velocity; X-ray topography; chemical etching; crystal growth; dislocation density distribution; etch pit density; lithium tetraborate single crystal; modified Bridgman method; seed crystal; Atmosphere; Chemicals; Crystals; Etching; Lithium; Nitrogen; Platinum; Surface acoustic wave devices; Surface acoustic waves; Velocity measurement;
Conference_Titel :
Ultrasonics Symposium, 2000 IEEE
Conference_Location :
San Juan
Print_ISBN :
0-7803-6365-5
DOI :
10.1109/ULTSYM.2000.922556
