Structural characteristics and optical properties of plasma assisted reactive magnetron sputtered dielectric thin films for planar waveguiding applications
Structural characteristics and optical properties of plasma assisted reactive magnetron sputtered dielectric thin films for planar waveguiding applications
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DOI：
10.1016/j.surfcoat.2012.05.110
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发表时间：
2012-07
影响因子：
5.4
通讯作者：
S. Pearce;M. Charlton;J. Hiltunen;J. Puustinen;J. Lappalainen;J. Wilkinson
中科院分区：
文献类型：
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作者：
S. Pearce;M. Charlton;J. Hiltunen;J. Puustinen;J. Lappalainen;J. Wilkinson
通过等离子体辅助反应双磁控溅射沉积氧化铝（Al 2 O3）、五氧化二钽（Ta 2 O 5）、氧化钛（TiO 2）、氧化钇（Y2 O3）和氧化锆（ZrO 2）薄膜，以确定它们作为稀土掺杂平面波导上转换激光器基质的适用性。研究了阴极、等离子体功率、氧气流量等工艺参数对沉积效果的影响，确定了操作工作点。使用功率和λ控制来优化每种材料的光学质量。通过使用λ控制反馈系统，磁控管功率波动以维持靶区域中的固定氧气流，从而减少材料上的化合物层生长并保持健康的沉积速率。每种薄膜的光学性质、结构和晶相均取决于工艺参数。X射线衍射（XRD）分析表明，薄膜从非晶到高度结晶取决于沉积条件。X射线光电子能谱（XPS）被用于表面成分分析，揭示了膜具有不同的化学计量比，这是由所选择的沉积参数控制的每种材料。薄膜层的波导损耗进行了研究和Ta 2 O 5被证明有一个平板波导损耗约1dB/cm在可见光和红外波长，使其成为理想的平面波导和激光应用。发现TiO 2、Y2 O3和ZrO 2以高度结晶相存款。在633 nm或红外区，TiO 2层中的波导是不可能的。Y_2O_3样品在1.3和1.5μm波长处有很低的损耗（2-4dB/cm），但在633 nm和833 nm处不存在波导。原子力显微镜显示粗糙的表面形貌TiO 2，Y2 O3和ZrO 2类似于他们的晶体生长与SEM图像确认规则的柱状晶结构的情况下，Y2 O3和ZrO 2。
Thin films of aluminum oxide (Al2O3), tantalum pentoxide (Ta2O5), titanium oxide (TiO2), yttrium oxide (Y2O3) and zirconium oxide (ZrO2) were deposited by plasma assisted reactive dual magnetron sputtering to determine their suitability as a host for a rare earth doped planar waveguide upconversion laser. The effect of deposition parameters such as cathode, plasma power and oxygen gas flows were studied and the operational working points were determined. Both power and lambda control were used to optimize the optical quality of each material. By using lambda control feedback system, the magnetron power fluctuates to sustain a fixed oxygen flow in the target area reducing the compound layer growth on the material and maintaining a healthy deposition rate. The optical properties, structure and crystalline phase of each film were found to be dependent on the process parameters. X-ray diffraction (XRD) analysis revealed that the thin films varied from amorphous to highly crystalline depending on the deposition conditions. X-ray photoelectron spectroscopy (XPS) was utilized for surface compositional analysis revealing that films had varying stoichiometric ratios which are controlled for each material by the deposition parameters chosen. The waveguide loss for the thin film layers was investigated and Ta2O5was shown to have a slab waveguide loss of ~1dB/cm at both visible and infra-red wavelengths making it ideal for planar waveguide and laser applications. TiO2, Y2O3and ZrO2were found to deposit in a highly crystalline phase. Waveguiding in the TiO2layers was not possible at 633nm or in the infrared region. The Y2O3samples gave low loss (2–4dB/cm) at the 1.3 and 1.5μm wavelengths but no waveguiding at 633nm or 833nm was possible. Atomic force microscopy showed rough surface topography for TiO2, Y2O3and ZrO2akin to their crystalline growth with the SEM images confirming the regular crystalline columnar structure for the case of Y2O3and ZrO2.