鐵電薄膜之熱輻射性質研究

Abstract

由於鐵電薄膜具有高介電性質，可以被應用於動態記憶體、鐵電記憶體以及光學元件，因此鐵電薄膜在高科技產業中是應用價值極高之產業，近年來研究鐵電薄膜電學與光學性質的文獻非常多，但是其量測的範圍大多僅止於可見光區段，因此本研究將使用波長範圍為0.7∼20mm的傅利葉轉換紅外線光譜儀(FTIR)，針對近、中紅外光區段來量測鍍在矽基材上之鋇鍶鈦、鉍鑭鈦以及鉍酸鈦薄膜在不同退火溫度、不同成份以及不同厚度下的穿透率與反射率，同時也量測鋇鍶鈦、鉍鑭鈦以及鉍酸鈦薄膜在不同溫度下之升溫反射率。並且利用NDL中n&k分析儀來量測鋇鍶鈦、鉍鑭鈦及鉍酸鈦薄膜在可見光區段的折射係數以及吸收係數。 本研究可以得知鋇鍶鈦、鉍鑭鈦及鉍酸鈦薄膜在可見光區段以及近、中紅外光區段之光學性質使其有更廣泛的應用。由實驗結果發現，鋇鍶鈦薄膜在厚度為0.4mm時有較高之折射係數以及吸收係數。鋇鍶鈦、鉍鑭鈦及鉍酸鈦薄膜之吸收係數及折射係數之最大值會出現在可見光區段，而在近、中紅外光區段之吸收係數幾乎為零。當溫度由30℃升至600℃時，其反射率差異不大，但有往較短波長移動之傾向。當溫度高於600℃時，由於鋇鍶鈦薄膜的結構已經改變，因此造成反射率往較長波長的方向移動。

Ferroelectric thin films have high dielectric properties, it has been widely used as the materials of Dynamic Random Access Memory (DRAM), Ferroelectric Random Access Memory (FRAM), and optical components. Consequently, ferroelectric thin film has been recoganized key component is the high tech industry. Recently, lots of researches had been carried out to investigate electrical and optical properties of ferroelectric thin films. However, most of the previous research focused on the measurement in visible light region. In this study, the transmittance and reflectance of barium strontium titanate, bismuth lanthanum titanate, and bismuth titanate thin films deposited on silicon substrates have been measured for variable annealing temperature, components, and thickness in the near-mid infrared wavelength region from 0.7∼20mm by using Fourier Transform Infrared Spectrometer (FTIR). At the same time, we also measured the up-temperature reflectance for variable temperature of barium strontium titanate, bismuth lanthanum titanate, and bismuth titanate thin films. And last, the refractive index and absorptive index of barium strontium titanate, bismuth lanthanum titanate, and bismuth titanate thin films have been measured in visible light region. In this study, we obtain optical properties of barium strontium titanate, bismuth lanthanum titanate, and bismuth titanate thin films by using FTIR technique at the visible light and near-mid infrared region for widely applications. Experimental results show that the higher refractive index and absorptive index of barium strontium titanate thin film occur at its thickness of 0.4mm. The value of absorptive index of barium strontium titanate, bismuth lanthanum titanate, and bismuth titanate thin films is close to zero at near-mid infrared region, but the maximum value of the refractive index is appeared at the visible light region; in addition, there is no manifest difference for the reflection index and has the trend to shift forward to the short-wavelength in the temperatures ranged from 30℃ to 600℃. For barium strontium titanate thin films, the reflection index has the trend to shift forward to the long-wavelength because of thin films structures have been transferred while upon the temperature of 600℃.