利用脈衝雷射蒸鍍法製備硒化鉍與摻銅硒化鉍薄膜之物性分析、兆赫波時域頻譜與超快載子動力學的研究

Abstract

在本論文中，我們利用脈衝雷射蒸鍍法製備硒化鉍與摻銅硒化鉍薄膜於藍寶石(0001)基板上；藉由X-ray 繞射儀(XRD)來探討改變製程溫度、壓力及脈衝能量下，其薄膜品質的比較。結合兆赫幅射時域技術與霍爾量測，研究其於不同製程溫度與摻銅所造成的物理特性。從光激發-探測系統、SEM表面形貌與EDS的成份分析來探討摻銅對於硒空缺議題上的影響，並經由雷射熱退火來改善薄膜的品質。最後，由光激發-中紅外技術來了解造成摻銅硒化鉍薄膜於其電漿邊緣所引發瞬時反射率劇烈變化的原因。

In this work, we have prepared Bi2Se3 and Cu0.125Bi2Se3 thin films were grown on sapphire(Al2O3)(0001) substrates by pulsed laser deposition(PLD) with various deposition temperatures、pressures and laser pulse energy. We analyzed their crystal structure and thin film quality utilizing X-ray diffraction(XRD). The physical properties in Bi2Se3 and Cu0.125Bi2Se3 thin films with various temperature conditions were studied by terahertz time-domain spectroscopy(THz-TDS) and Hall measurement. Combined with the scanning electron microscopy(SEM)、energy dispersive spectrometer(EDS) and optical pump-probe spectroscopy(OPOP), we discuss the problem of Se vacancies in Cu doping the Bi2Se3 thin films. Phonon dynamics in Bi2Se3 and Cu0.125Bi2Se3 thin films were modified by laser annealing. The dramatic change of the differential transmission spectra (ΔR/R) have been observed when the wavelength of the mid-infrared probe beam is near the minimum plasma edge.