電子束蒸鍍碲化銻於玻璃基板上之最佳化製程研究

Optimal Process of Electron Beam Evaporation of Sb2Te3 on the Glass Substrate

彭成浩(Cheng-Hao Peng)

指導教授 ： 張合

國立臺北科技大學/機電學院/製造科技研究所/碩士(2010年)

摘要

本研究係利用電子束蒸鍍法(Electron beam evaporation)將熱電晶粒Sb2Te3在玻璃上蒸鍍出Sb2Te3薄膜；並經由不同之蒸鍍製程參數及薄膜退火條件之實驗測試，以獲得較佳之薄膜熱電優值(ZT值)。ITO導電玻璃經由丙酮(Acetone)、異丙醇(Isopropyl Alcohol；IPA)及去離子水(DI water)以超音波震盪洗淨後，在真空度為5×10-6torr下進行蒸鍍作業，並經由不同之蒸鍍製程，以獲得最佳的基板溫度，以及最佳的薄膜退火溫度及時間，而使所製備出之Sb2Te3薄膜具有較佳的電阻率(ρ)及Seebeck係數，以及最高的功率因子(Power Factor)。本文利用XRD pattern檢測薄膜微結構之組成，以霍爾量測系統量測載子濃度(carrier concentration)，並透過SEM來觀察薄膜表面微結構之形貌。另外，以Van der Pauw四點探針法量測薄膜之電阻率，以及以3ω法量測薄膜之熱傳導係數。經初步實驗結果顯示，隨著蒸鍍溫度的不同，會造成Sb2Te3薄膜中Sb2Te3晶粒大小的不同，而導致薄膜之Seebeck係數有所不同；而將薄膜經由退火處理後，即可降低薄膜缺陷，並提高載子移動性(mobility)並進而提升薄膜之電導率。當設定基板之溫度為200 ℃時，經由蒸鍍製程所製備出之Sb2Te3薄膜，再經由220℃之退火處理60分鐘後，此Sb2Te3薄膜之Seebeck係數可由87.6μV/K增加至177.7μV/K，電阻率則由6.21mΩ-cm降為2.53mΩ-cm，而功率因子(Power Factor)可達到1.24 10-3W/K2m之最大值；此外，在前述相同蒸鍍與退火條件下所致備出Sb2Te3薄膜，以3ω法量測出薄膜之熱傳導係數為0.93W/mK，經過計算後ZT值為1.33(10-3)。

關鍵字

ZT值 ； Seebeck係數 ； 電子束蒸鍍 ； 碲化銻

並列摘要

This study adopts Sb2Te3 thermoelectric grains to evaporate Sb2Te3 thin films by electron beam evaporation and acquires better thermoelectric merit figure (ZT value) through different evaporation process parameters and film annealing conditions tests.
ITO conductive glass is cleaned by acetone, isopropyl alcohol (IPA) and deionized water (DI water) by ultrasonic vibration and evaporated at vacuum, 5×10-6torr to obtain the optimal substrate temperature, film annealing temperature and time via different evaporation processes to make Sb2Te3 film have better resistivity (ρ), Seebeck coefficient and the highest power factor. This study uses X-ray diffraction (XRD) pattern to measure the thin film microstructure, adopts Hall measurement system to test the carrier concentration and observes the morphology of thin film surface microstructure by scanning electron microscope (SEM). Besides, Van der Pauw four-point probe is employed to measure the resistivity of thin films and 3ω method is used to test thermal conductivity of thin films. Results show that the differences of temperature will cause different sizes of Sb2Te3 grains in Sb2Te3 films and different Seebeck coefficient of thin films. When the temperature of substrate is set at 200℃and annealed at 220℃ for 60 minutes to prepare for Sb2Te3 thin films, Seebeck coefficient can increase from 87.6μV/K to 177.7μV/K, resistivity can reduce from 6.21mΩ-cm to 2.53mΩ-cm and power factor can reach the maximum – 1.24 10-3W/K2m. Moreover, above-mentioned Sb2Te3 thin films fabricated under the same evaporation and annealing conditions are tested thermal conductivity with 0.93W/mK by 3ω method and calculated ZT value –1.33(10-3).

並列關鍵字

ZT value ； Seebeck coefficient ； electron beam evaporation ； Sb2Te3 thin film

參考文獻

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