脉冲激光沉积法在GaN基片上制备c轴取向LiNbO_3薄膜

Microstructures and Properties LiNbO_3 Films Grown by Pulsed Laser Deposition on GaN Substrate

采用LiNbO3单晶靶材，以激光脉冲沉积方法在六方GaN（0001）基片上沉积制备c轴取向的LiNb03薄膜。利用x射线衍射仪（XRD）、扫描电子显微镜（SEM）和原子力显微镜（ARM）研究了沉积温度和氧气压强对生长的薄膜的相组成、外延关系、表面形貌、晶粒大小的影响。结果显示，沉积温度500℃、氧分压20～30Pa是在GaN基片上生长C轴取向LiNbO3薄膜的最优生长条件。XRD分析表明，生长的LiNbO3薄膜具有两种晶畴结构，其外延关系分别为[1-100]（0001）LiNbO3/／[11-20]（0001）GaIN和[10-10]（0001）LiNbO3／／[-12—10]（0001）GaN。SEM和AFM对薄膜的表面形貌表征表明，在最优生长条件下沉积的薄膜表面平整，致密度好。

The LiNbO3 films were grown by pulsed laser deposition （PLD） on （0001） GaN substrate.The impacts of deposition conditions, such as the deposition rate, laser power, substrate temperature, and oxygen partial pressure, on its microstructures and its ferroelectric property were studied. The films were characterized with X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The results show that the fairly dense and compact LiNbO3 films grown under optimized conditions, is c-axis oriented with two distinct epitaxial growth modes： [ 1-1001 （0001） LiNbO3//[ 11- 20] （0001）GaN and [ 10-10] （0001） LiNbO3//[-12-10] （0001） GaN. Possible mechanism responsible for the epitxial growth was also tentatively discussed.