在本研究中，首先利用釕酸鍶(SrRuO3,簡稱SRO)材料成長在鈦酸鍶(SrTiO3,簡稱STO)基板上，探討濺鍍系統中的各個參數，分別對於薄膜生長的影響，以期望能瞭解參數調製的規則，達到控制薄膜以層狀(Layer-by-Layer)的方式成長。接下來以層狀成長為基礎，成長鐵電材料鈦酸鋇(BaTiO3,簡稱BTO)於SRO/STO系統上。製作不同BTO厚度系列，探討失配應變對鐵電性質的影響。
我們發現由晶格不匹配造成的失配應變會讓薄膜成長的模式由層狀成長(layer by layer)轉為先層狀後島狀(layer then island)的成長，存在一臨界厚度，本實驗BTO/SRO系統介於6~15nm之間。我們成長不同BTO厚度的樣品，由x-ray晶相鑑定計算個別樣品所受的失配應變。之後對樣品作微觀壓電係數d33之量測，發現在外加電場下，受到失配應變程度越大的樣品，其壓電係數越小。推測是由於失配應變束縛住介面幾層的晶格，使其無法隨外加電場做形變。另外我們將樣品作介電常數對頻率的分析，發現隨著所受失配應變的程度越大，其介電常數的值越小，而弛豫時間隨著失配應變的程度增加而變大。這個結果說明了在失配應變較大的條件下，相當於是提高粒子從某一能態過渡到另一穩定態所需要跨越的位障，也就是受到外加電場時，電偶極翻轉所需要的時間較長。

In this study, we deposited SrRuO3 (SRO) on SrTiO3 (STO) substrate to investigate how the parameters of sputter system affected the growth mode during the thin-film deposition process. The objective is to build a rule for controlling deposition parameters so that the thin films can grow layer-by-layer. Based on layer-by-layer growth, we deposited epitaxial BaTiO3 (BTO)/SRO/STO ferroelectric heterostructure to study how mismatch-strain affected the ferroelectric characteristics.
We find out that the mismatch-strain will change the growth mode from layer-by-layer to layer-then-island, and the critical thickness of the BTO/SRO materials system deposited by sputter is between 6~15 nm. We deposited BTO with different thickness, and calculated the mismatch-strain of each samples from x-ray spectrum. We also measured the piezoresponse constant d33 of each samples. We find out that with the mismatch-strain increase, the d33 decrease. It’s probably because the mismatch-strain restricted the adjacent lattices at the interface so that it can’t be extended along the external electric field. Moreover, with the mismatch-strain increase, the dielectric constants decrease, whereas the relaxation time increases. This result implied that the mismatch-strain raise the energy barrier of polarization switching so that it have to spend more time to transit from one energy state to a more stable state.

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