$Ti:LiNbO_3$ 도파로 제작을 위한 열처리 과정 동안 강유전 도메인 특성에 미치는 영향

Ferroelectric domain inversion in $LiNbO_3$ crystal plate during heat treatment for Ti in-diffusion

  • 양우석 (전자부품연구원 나노바이오포토닉스팀, 항공대학교 항공재료학과) ;
  • 이형만 (전자부품연구원 나노바이오포토닉스팀) ;
  • 권순우 (항공대학교 항공재료학과) ;
  • 김우경 (전자부품연구원 나노바이오포토닉스팀) ;
  • 이한영 (전자부품연구원 나노바이오포토닉스팀) ;
  • 윤대호 (성균관대학교 신소재공학과)
  • Yang, W.S. (Nano Bio-photonics Team, Korea Electronics Technology Institute, Department of Materials Engineering, Hankuk Aviation University) ;
  • Lee, H.Y. (Nano Bio-photonics Team, Korea Electronics Technology Institute) ;
  • Kwon, S.W. (Department of Materials Engineering, Hankuk Aviation University) ;
  • Kim, W.K. (Nano Bio-photonics Team, Korea Electronics Technology Institute) ;
  • Lee, H.Y. (Nano Bio-photonics Team, Korea Electronics Technology Institute) ;
  • Yoon, D.H. (Department of Advanced Materials Engineering, Sungkyunkwan University)
  • 발행 : 2005.06.30

초록

[ $Ti:LiNbO_3$ ], 광도파로 제작을 위해 큐리온도$(T_c)$ 아래에서 백금박스 내에서 알곤 과 산소 분위기 내에서 열처리 과정 동안 기판 표면의 강유전 도메인 특성 변화를 관찰하였다. 열처리 된 $LiNbO_3$ 기판의 +Z면의 경우 전체적으로 약 $1.6{\mu}m$ 두께로 도메인 반전이 이루어 졌으며, 표면에서 etch hillock이 관찰되었다. $LiNbO_3$ 결정 표면의 Li 이온이 외부로 확산 되는 영향을 감소시킬 수 있는 환경에 있는 기판 면에서 하나의 도메인이 관찰되었으며, 이때 결정 표면에서의 식각특성, 결정성 및 양이온 분포변화에 관하여 X-선 회절, AFM 및 SIMS를 이용하여 분석하였다.

It is demonstrated that the annealing process for Ti in-diffusion to z-cut $LiNbO_3$ at temperature lower than the curie temperature in a platinum (Pt) box can cause a ferroelectric micro-domain inversion at the +z surface and Li out-diffusion, therefore which should be avoided or suppressed for waveguide type periodically poled lithium niobate (PPLN) devices. The depth of the inversion layer depends on the Ti-diffusion conditions such as temperature, atmosphere, the sealing method of $LiNbO_3$ in the Pt box and crystal orientation is experimentally examined. The result shows that the polarization-inverted domain boundary appears at the only +z surface and its thickness is about $1.6{\mu}m$. Also, for the etched $LiNbO_3$, surface the domain shape was observed by the optical microscope and atomic force microscopy (AEM), and distribution of the cation concentrations in the $LiNbO_3$ crystal by the secondary ion mass spectrometry (SIMS).

키워드

참고문헌

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