我們以光調制反射光譜(PR)來研究由分子束磊晶法(MBE)長成的InGaAs/GaAs單量子井結構在不同溫度及不同偏壓下其電-光性質的變化。
實驗的樣品共有兩塊，分別以(100)與(111)B的基底所長成，樣品結構包含了寬度為60A的單量子井外，並在樣品近表面500A處有Si的單層摻雜
(delta-doping)濃度為5*10^{12} cm^-2。實驗的光譜在GaAs能隙之上呈現出Franz-Keldysh振盪(FKO)，GaAs能隙之下為量子井子能階躍遷的訊號。我們以理論模型計算量子井子能階的躍遷能量，並與實驗譜圖相比較，經由振盪譜形的分析，推算出樣品表面的內建電場。

The electrooptical properties of (100) and (111)B InGaAs/GaAs single quantum wells (SQW) have been studied by photoreflectance (PR) spectroscopy at various temperetures and
under different biases. The samples used in our experiments were grown by molecular-beam-epitaxy (MBE) on the (100) and (111)B GaAs substrates separately. There is a Si delta-doping layer of 5 *10^{12} cm^-2 at 1000A away from the SQW and 500A
under the GaAs surface. The PR spectra features above the nergy gap of GaAs are the Franz-Keldish oscillations (FKOs), and features below the energy gap of GaAs are the excitonic interband transitions. Theoretical calculations have been performed to identify the origins of the various spectral features. By the analysis of the line shapes of the FKOs, we obtained the internal electric fields of the samples.

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