鋇鍶鈦薄膜熱輻射性質之實驗研究

Abstract

摘要 由於鋇鍶鈦薄膜具有高介電常數、低漏損電流、低介電損失等特性，所以鋇鍶鈦薄膜目前正廣泛被研發作為動態隨機存取記憶體（DRAM）電容器中的替代介電材料。除此之外，鋇鍶鈦薄膜也可以應用於光電元件製作，例如光導管、光學開關以及紅外線熱像儀的偵測器材料等。在過去，有關於鋇鍶鈦薄膜性質的研究，都主要是在探討各種不同的鍍膜方式與鍍膜參數對於薄膜結構與可見光範圍之光學性質的影響，到目前為止，針對鋇鍶鈦薄膜在紅外線波段的光學性質與熱輻射性質的研究還相當的少。 本研究的主要目的是應用傅利葉轉換紅外線頻譜儀（FT-IR）量測在紅外線波段（0.64μm到19.6μm）下，不同厚度的鋇鍶鈦薄膜鍍在石英、氧化鎂與矽基材上的穿透率及反射率，再應用比爾定理，利用實驗量測得到的穿透率、反射率，計算鋇鍶鈦薄膜薄膜的消散係數；同時也應用物質能量守恆的關係，由量測到的穿透率、反射率來計算鋇鍶鈦薄膜試片的吸收率。如此一來就可以知道鋇鍶鈦薄膜在紅外線波段的吸收特性及光學性質，這些性質可以提供未來設計相關元件。由實驗結果可發現，鋇鍶鈦薄膜在紅外線波段（0.64μm到10μm）具有很高的消散係數，同時，鋇鍶鈦薄膜在紅外線波段（0.64μm到10μm）也具有很高的穿透率，很適合於為光學元件的製

ABSTRACT Barium strontium titanate (Ba,Sr)TiO3 (BST) thin films are being widely investigated as alternative dielectrics for ultra large scale integrated circuits (ULSIs) DRAM storage capacitors due to its high dielectric constant, low leakage current, small dielectric loss. In addition, the BST thin films can also be used in the optical devices such as planar waveguides, optical switches or the sensor material for thermal imaging detector. In the past, some investigations have focused on the dependence of optical properties and film structure on the deposition parameters of thin films deposited by various methods such as sputtering, sol-gel process, pulsed laser deposition and radio-frequency magnetron sputtering. But, no detailed studies have elucidated the optical and thermal radiative properties related to the BST thin films in the Infrared spectrum. In this study, the transmittance and reflectance of BST thin films for several different thickness deposited on both Fused-Quartz, MgO and silicon substrates are measured using FT-IR (Fourier Transform Infrared Spectrometer) from 0.64 mm to 19.6 mm. Then, by Beer’s law, the extinction coefficient of the BST films can be evaluated. Using the energy conservation law, the absorptance of the BST thin-film samples can also be figured out from the transmittance and reflectance. Therefore the absorptive characteristics and optical properties will be known from these radiative properties, and are offered to be references in manufacturing and research. The results showed that the transmittance and the extinction coefficient of BST thin films are very high between 0.64mm and 10mm. With the high transmittance, the BST thin film is suitable for the optical devices manufacturing.