以飛秒光激發探測系統研究硒化鉍薄膜之超快動力學

Abstract

在本論文中，我們使用脈衝雷射蒸鍍法在藍寶石基板上製備硒化

鉍薄膜，並利用改變一系列基板溫度使薄膜成長條件最佳化。藉由 X

光繞射、掃描式電子顯微鏡、霍爾儀器的量測來觀察樣品的晶格結構、

表面樣貌及測量其載子濃度。透過本研究群所建立之超快光激發探測

技術，研究其超快載子動力學行為。我們利用同調光頻聲子、同調聲

頻聲子分析硒化鉍薄膜的瞬時反射率的高頻以及低頻振盪訊號並發

現薄膜表面呈現鉍富含的情況。

In this thesis, we have prepared bismuth selenide thin films which

were grown on Sapphire(0001) substrates by pulsed laser deposition(PLD)

and change various substrate temperature to get optimization. The surface

morphology of samples with various substrate temperature was studied

by means of Scanning Electron Microscopy (SEM).The crystal structure

and carrier concentration were investigated by means of X-Ray

Diffraction (XRD) and Hall measurement.The ultrafast carrier dynamics

behavior have been studied by Optical Pump-Probe measurement (OPOP) .

We use coherent optical phonon、coherent acoustic phonon to anlyze

high frequency and low frequencyΔR/R singnal then find the appearance

of Bi-rich condition on thin film surface.