我們以光調制反射光譜(PR)來研究由分子束磊晶法(MBE)長成的砷化鎵(
GaAs)/ 砷化鎵銦 (InGaAs)之異質結構,在不同溫度下內建電場的變化,實
驗結果譜形相當複雜,將此譜形作擬合與分析並配合加偏壓的實驗做比對,
可辨識出光譜中各部份來源,在光子能量大於砷化鎵能隙處,有兩組譜形重
疊,分別來自第二層及第四層的砷化鎵，因第二層的內建電場較大,所以有
明顯大週期的FKO,而在光子能量大於砷化鎵銦能隙處也有兩組譜形重疊,
是來自第一層及第三層的砷化鎵銦,另外由譜形擬合與分析也可推算出內
建電場隨溫度變化關係,並與數值理論計算做比較。

The varities of built-in fields of the MBE grown GaAs/InGaAs
heterostructures have been studied by the photoreflectance
spectroscopy(PR) at various temperature.The spectra were
complicated and contained four types of oscillations in
different spectra regions.The origins of different features in
the spectra were identified by comparing lineshape fitting and
analysis with experiment result of appling bias voltage on
sample. Above the energy gap of GaAs,there were two types of
spectra oscillations. The one with large oscillatin period was
due to the modulation of the high built-in field in second
layer.The lineshape oscillations above the energy gap of InGaAs
originated from first and third layers which were both n-type
doped. The built-in fields were deduced from the spectra
fitting and analysis,and compared with the numerically
calculated results.
The varities of built-in fields of the MBE grown GaAs
InGaAs