InGaAs 應變量子阱之光調制光譜研究

Abstract

本研究主要是利用光調制反射光譜(Photoreflectance:PR)來量測並 分析InGaAs/GaAs及InGaAs/InGaAsP 應變量子阱結構的電子能態.對於 InGaAs/GaAs應變量子阱雷射結構,除了量測到低階躍遷(1.336 eV)外,尚 有由漸變折射率異質接面產生的Franz-Keldysh振盪光譜,可據以分析其內 部電場強度,而InGaAs/InGaAsP應變量子阱除了低階躍遷(1.276 eV)外,尚 有高階躍遷(1.386 eV).另外在不同的雷射強度調制下發現其改變光調制 反射光譜譜形,這在電場調制反射光譜(Electroreflectance:ER)的多層結 構量測及理論都已得到證實, 但在光調制反射光譜量測上還欠缺證據.除 此之外採用三光源PR也證實有效的減弱表面電場.另一方面從實驗數據推 導得知InGaAs的interband hydrostaticpressure deformation potential 約為 -6.9 eV. 在低溫量測下,由於較小的展寬係數,進而更加 容易分辨多層結構中的各躍遷 In this thesis,the electronic states of InGaAs/GaAs and InGaAs/InGaAsP strain quantum wells were studied experimentally by using photoreflectance (PR) spectroscopy and numerically analyzed by beam propagation method(BPM). Sweeping PR system was set up to measure PR spectra of the graded-indexseparated confinement heterostructure (GRINSCH) 600nm-InGaAs/GaAs/ AlGaAslaser device. The spectrum feature of 1.335 eV is attributed to the ground- state electron-heavy hole transition is closed to the BPM analysis with E1 ehhtransition of 1.331 eV.The low-level and excited state transition with energies1.276 eV and 1.386 eV were obtained by PR measurement and fitting process for 600nm-InGaAa/1000nm- InGaAsP multiple strain quantum wells. The fundamental transition is closed to the photoluminescence(PL) feature of 1.2757 eV. Basedon the experimental data and BPM anylysis, we induced that the interband hydrostatic pressure deformation potential is around -6.9 eV for InGaAs