同時熱壓與退火處理3-D碲硒(銻)化鉍薄膜熱電性質之研究

Effect of Hot pressing-Annealing on Thermoelectric Properties of 3-dimension Bismuth-Telluride-based Film Electrodeposited on Polystyrene Sphere Template

李宗儒(ZONG-RU LI)

指導教授 ： 林昭任

國立中正大學/工學院/化學工程學系/碩士(2014年)

摘要

本實驗為利用刮塗法在不鏽鋼基材上製備聚苯乙烯球模板，並於常壓下電鍍具有三維結構的碲化鉍基熱電薄膜後，再進行同時熱壓退火處理。首先探討該材料的電化學特性以及沉積電位與組成的關係，再研究同時熱壓退火處理對薄膜各項性質的影響(包含厚度、Seebeck係數、電阻率、載子濃度以及遷移率)。電鍍方式採定電位沉積法，固定溫度30oC、轉速340rpm，參考電極為3M Ag/AgCl。實驗結果顯示，p-type沉積電位為-0.2V時，鍍膜有較好的組成，n-type電位則為-0.06V。經過同時熱壓退火後，試片的Seebeck係數與電阻率皆則隨著溫度與壓力的提升而下降，這是由於試片經過同時熱壓退火處理後，高壓使得原始的鬆散結構變得緊密、高溫讓原子重新排列並消除多種的晶格缺陷，因此電導率大幅提高，雖然試片經同時熱壓退火後導熱性也會提升，但上升的幅度相比於電導率小的太多，故Seebeck係數仍呈現下降的趨勢。隨著同時熱壓退火的時間加長，可有效的降低載子濃度並提升遷移率。在最後結果的部分，Power factor的最大值皆出現於以溫度290oC、壓力195kgf/cm2進行60分鐘之電流輔助同時熱壓退火時，p-type的最大值為555μW/K2m，n-type則為397μW/K2m。

關鍵字

碲化鉍基 ； 電沉積 ； 聚苯乙烯球模板 ； 熱電 ； 熱壓法

並列摘要

This study was to investigate the properties of three-dimensional Bi2Te3-based thin films prepared by potentiostatic electrodeposition technique onto three-dimensional polystyrene templates which were formed on stainless steel substrates via blade coating method. Temperature were fixed at 30oC and agitated at a speed of 340 rpm during electrodeposition process. A hot pressing-annealing method was applied after electroplating process to enhance thermoelectric properties. In order to obtainthe optimal operational conditions, these films were used for electrochemical, compositional and thermoelectrical analysis. It was found that p-type Bismuth-Antimony-Telluride and n-type Bismuth-Telluride-Selenium thin films which were deposited at a constant potential of -0.2V and -0.06V vs. Ag/Ag Clare the closest to ideal composition. The thermoelectrical analysis results show that both Seebeck coefficient and electrical resistivity were reduced after hot pressing treatment. That could be attributed to the raising pressure and temperature which forced atoms to rearrange during hot pressing-annealing process. The treatment will further reduce the lattice defects and make structure tighter. Although thermal conductivity would also increased by this phenomenon but it is almost disproportionate compared to electrical resistivity drop, and the Seebeck coefficient decreases. The carrier concentration and mobility presented down ward and upward trend respectively with processing time extend. In terms of performance, the maximum power factorof the films studies is 555μW/K2m for p-type Bismuth-Antimony-Telluride and 397μW/K2m forn-type Bismuth-Telluride-Selenium. Both of these two samples were prepared under the conditions of 290oC and 195kgf/cm2 after current assisted hot pressing-annealing treatment for 60 min.

並列關鍵字

Bi2Te3-based ； electrodeposition ； polystyrene template ； Thermoelectric ； hot pressing

參考文獻

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