| 摘要 |
PURPOSE:To obtain single crystal with few grid defects by preparing the ferroelectric crystal expressed in a composition formula LiNb1-xTaxO3 (0<=x<=0.9) by drawing up an axis C while the rotation direction of grown crystal is set clockwise and by applying DC electric field for poling with the seed side being set positive and the tail side negative. CONSTITUTION:When the ferroelectric signal crystal expressed by the composition formula LiNb1-xTaxO3 (0<=x<=0.9) is prepared by a Czochralski method, the seed is dipped in melted material and rotated clockwise at about 10rpm and at the draw- up speed of about 3mm./h, with the axis of the crystal being made to be the axis C. Next, so as to turn the crystal thus obtained into the state of single domain, first the grown crystal is kept for two hous at the raised temperature of about 1,150 deg.C, later the DC electric field of 2V/cm is impressed with the seed side being positive and the tail side negative, and then, the electric field being removed, gradual cooking is applied. Since the method of drawing-up of the axis C and clockwise rotation is adopted in this way, the number of etch pits is reduced down to 50/cm<2> and thus excellent characteristic is obtained. |
