利用時間解析量測技術研究氮砷化銦鎵量子井的超快載子動力行為

Abstract

在本論文中，我們比較由金屬有機化學氣相沈積法(MOCVD)成長的砷化銦鎵和氮砷化銦鎵單層量子井的超快載子動力學。氮砷化銦鎵的能隙因為氮的加入比砷化銦鎵的能隙小很多，可以發出波長為1.45μm 的光。我們利用飛秒時析反射量測研究載子的鬆弛過程。比較這兩個樣品在不同波長的量測結果，發現短波長下由於能隙收縮，反射率變化為負；長波長下由於能帶填充，反射率變化則為正。另外(氮)砷化銦鎵有兩個生命期，我們推測較短者為電子電洞散射所致，較長者在砷化銦鎵和氮砷化銦鎵中，分別為熱聲子效應和受激輻射。

The comparative analysis of the ultrafast carrier dynamics of metal-organic chemical vapor deposition (MOCVD) grown In0.4Ga0.6As and In0.4Ga0.6As0.98N0.02 single quantum wells (SQW) is reported. The incorporation of a low content N in InGaAsN reduces the band-gap energy significantly and allows emission wavelengths shift to 1.45 μm. Carrier dynamics were investigated by femtosecond time-resolved photoreflectance measurement at 800/820 and 880 nm with various pump intensities. Comparison with these two samples at different pumping wavelengths indicates that ΔR is negative at pumping wavelength < 820nm due to bandgap renormalization; ΔR is positive at 880nm due to band filling effect. Furthermore, there are two lifetimes in InGaAs(N), and we speculate that the shorter one is due to electron-hole scattering. The longer one is due to hot phonon decay in InGaAs and stimulated emission in InGaAsN.