氮摻雜不均對於InGaAsN/GaAs量子井電性之影響

Abstract

當量子井層中的N原子摻雜不均勻時，將同時造成N原子的成份波動效應以及N原子群聚效應，而N原子的摻雜的均勻程度受到長晶條件(長晶速率)、長晶後的熱退火...等因素所影響。N原子成份波動效應會對於InGaAsN量子井電子放射特性造成影響，嚴重的N原子成份波動效應將使得InGaAsN QW電子能階分佈較廣，並且整體而言InGaAsN QW的電子能階會在較深處，因此無法觀察到QW中電子的穿隧放射特性。我們也針對N相關之局部侷限能階作進一步的探討。我們運用DLTS量測來探討N相關之局部侷限能階對於InGaAsN 量子井的電子捕捉特性， N相關之局部侷限能階訊號越大(缺陷數量越多)的樣品，其C-V量測中的量子井空乏平台長度就越短(QW中電子數量越少)。最後，我們探討N相關之局部侷限能階的存在對於光激發載子之影響。當N相關之局部侷限能階存在於InGaAsN QW樣品時，其可延伸光電容對光能量的反應範圍，並且，N相關之局部侷限能階可為光激發載子提供一個額外的電流路徑。

Non-uniform nitrogen doping in quantum well layer can lead to severe N-composition fluctuation and clustering of N atoms simultaneously. The uniformity of nitrogen doping can be modulated by different growth conditions (growth rate) or RTA. N-composition fluctuation can influence the quantum well electron emission behavior. A severe N-composition fluctuation can lead to a broad distribution of quantum well electron states; moreover, it deeper the overall quantum well electron states, therefore, suppresses the tunneling emission of QW electron states. We also take a closer look at the N-related localized states (=N clusters localized states, LS). The electron capture properties of LS can be discussed through DLTS measurements. The larger LS signals (higher defect concentration) in the sample are, the shorter quantum well depletion platform (fewer electrons in quantum well) in C-V measurements will be. Eventually, we discuss the properties of light-induced excess carriers in N-related localized states. LS can extend response range of photocapacitance versus photon energy, and contribute an additional current path to light-induced excess carriers.