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使用TEM和DLTS分祈了慢退化GaAlAs DH LEDs的缺陷,以弄清其退化机理。用TEM探测到了簇状缺陷(4~10nm)和很小的位错环(15~50nm)。我们采用DLTS技术详细地观测了LEDs中深能级缺陷密度增加的两个阶段。在这些观测基础上,讨论了电流感生缺陷形成的模型。图1(a)给出LED在169℃下工作7000小时后,在其有源层中观察到的缺陷的TEM照片。观察到簇状缺陷(c)和小位错环(L)均匀地分布在材料中,但尺寸不规则。图1(b)示出1张弱电子束TEM照片。测量到
TEM and DLTS were used to explain the slow degradation of GaAlAs DH LEDs to clarify their mechanism of degradation. Clustered defects (4 ~ 10 nm) and very small dislocation loops (15 ~ 50 nm) were detected by TEM. We use DLTS technology to observe in detail the two stages of increased density defects in deep-level LEDs. Based on these observations, the formation of current induced defects is discussed. Figure 1 (a) gives a TEM photograph of the defects observed in the active layer of the LED after 7000 hours of operation at 169 ° C. Clustered defects (c) and minor dislocation loops (L) were observed to be uniformly distributed in the material but irregular in size. Figure 1 (b) shows a weak electron beam TEM photograph. Measured