• 作者： 黃鶯聲; 林得裕; 程光蛟
• 作者服務機構： 國立臺灣科技大學電子工程技術系; 國立海洋大學電機工程學系
• 中文摘要： 本論文利用調制反射光譜探討以數位梯度法製備之非對稱三角形量子井（asymmetric triangular quantum well，簡稱ATQW）及對稱矩形量子井（symmetric rectangular quantum well，簡稱SRQW）之光學特性。量測溫度範圍為20至300 K，其中壓電調制屬於應力調制，而輕電洞帶對應力較敏感。詳細比較壓電調制及光子調制光譜，提供一種簡易方法能夠辨識量子井內輕電洞與重電洞之躍遷訊號，對光譜訊息的解析有所助益。運用包絡函數近似計算ATQW及SRQW之躍遷能量與實驗值相互比較，判定以數位梯度法製備實驗樣品，確實能長出預先設計的結構。同時探討溫度改變對量子井帶間躍遷能量的影響。此外也討論溫度變化對量子井結構11H激子躍遷信號展寬參數的影響。
• 英文摘要： We have studied the piezoreflectance (PzR) spectra related to intersubband transitions from several(001）GaAs/AlGaAs structures fabricated by means of molecular beam epitaxy using the digital alloycompositional grading (DACG) method in a temperature range of 20 to 300 K. These samples includean asymmetric triangular quantum well (ATQW) and three symmetric rectangular quantum wells (SRQW)with different unit cells (方程式無法摘錄) ．A comparison of the relative intensityof the heavy- and light-hole related features in the PzR spectra and those from photoreflectance measurementreveals the contribution of the strain dependence of the energies of the confined states that allows us toidentify unambiguously the features associated with the heavy- and light-hole valence bands．Comparisonof the observed intersubband transitions with the envelope function calculations provides a self-consistentverification that the DACG method generated the desired potential profiles for the ATQW．For SRQWs,the 12.5 A unit cell sample essentially has the characteristics of the intended analog configuration whilethe other two samples displayed observable differences．Furthermore, detailed study of the temperaturedependence of the excitonic transition energies indicates that the main influence of temperature on thequantized transitions is through the temperature dependence of the band gap of the constituent materialin the well．An anomalous behavior of the temperature dependence of the linewidth of the fundamentalconduction to the heavy-hole excitonic feature of the samples is observed, and the possible contributionsof the broadening parameters are discussed.
• 中文關鍵字： modulation spectroscopy; piezoreflectance; digital alloy compositional graded structures; GaAs/AlGaAs; quantum well
• 英文關鍵字： --