AlGaN合金中局域态和极化电场的竞争机制

通过MOVPE方法生长了不同Al组分的3块Al_xGa_1-xN样品，利用稳态光谱和时间分辨光谱对其样品的光学特性进行了分析。鉴于影响氮化物发光性质的极化电场或局域态的单一机制不能充分解释我们的实验现象，提出了局域态-内部极化电场竞争的机制。通过对实验数据的分析，得出如下重要结论：样品PL峰位蓝移的温度起点基本对应于局域态和极化电场起作用的交替点，PL峰位发生蓝移的温度起点与光强-温度曲线的斜率出现明显变化的温度点一致；随着温度的升高，若AlGaN合金样品中PL峰位存在二次蓝移，则说明样品中电场分布不均匀。

Competition Mechanism of Local State-internal Polarization Electric Field in Algan Alloy

Three Al_xGa_1-xN samples were grown by metal organic chemical vapor phase deposition (MOCVD), and their optical properties were analyzed by the steady-state and time-resolved photoluminescence (PL) techniques. In view of the fact that the experimental phenomena cant be fully explained by a single mechanism of polarization electric field or that of local state, which remarkably influence luminescent properties of nitrids, the competition mechanism between local state and internal polarization electric field was proposed. By analyzing the experimental data, two crucial conclusions are drawn. First, the temperature starting point of PL peak blue-shift basically corresponds to the shift point between the effect of local state and the effect of polarization electric field. The temperature starting point of PL peak blue-shift is well consistent with the temperature point where the slope of illuminant intensity-temperature curve changes significantly. Then, there is non-uniform polarization electric field distribution in the sample if the PL peak has two blue-shifts with the temperature increasing in AlGaN alloy.