Diffusivity, solubility and thermodynamic modelling of diffusion growth of Ga3+-doped LiTaO3 thin film for integrated optics

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

3 Scopus Citations
View graph of relations


  • De-Long Zhang
  • Qun Zhang
  • Pei Zhang
  • Jian Kang
  • Wing-Han Wong
  • Dao-Yin Yu


Original languageEnglish
Pages (from-to)93-99
Journal / PublicationJournal of Chemical Thermodynamics
Publication statusPublished - 1 Jun 2016


A thermodynamic study was performed on diffusion growth of Ga3+-doped LiTaO3(LT) thin film for integrated optics. Some Ga3+-doped LT thin films were grown on LT surface by in-diffusion of homogeneously coated Ga2O3 film at the temperature range of (1273 to 1473) K. After growth, the refractive indices at Ga3+-doped and un-doped surface parts were measured by prism coupling technique and Li composition there was evaluated from the measured refractive indices. The results show that Ga3+ dopant has small effect on the LT index. Li2O out-diffusion is not measurable. The Ga3+ profile in the grown thin film was analysed by secondary ion mass spectrometry. It is found that the grown Ga3+ ions follow a complementary error function profile. A thermodynamic model for Ga3+ diffusion growth is suggested and verified experimentally. From the measured Ga3+ profiles, some thermodynamic parameters were obtained. These include diffusivity, diffusion constant, chemical activation energy, solubility, solubility constant and enthalpy of solution. These parameters are crucial to design and growth of a desired Ga3+-doped LT thin film for integrated optics. Comparison shows that Ga3+ grows in LT two orders faster than Ti4+ because of its smaller radius. Ga3+ diffusivity/solubility in LT is one order/1.5-fold lower than in LiNbO3 because Ta has a larger atomic mass and hence a lower mobility than Nb.

Research Area(s)

  • Ga3+ diffusion growth, LiTaO3, Thermodynamic properties

Citation Format(s)