InN量子点的液滴外延及物性表征

Droplet Epitaxy and Physical Characterization of InN Quantum Dots

由于1. 55μm波段广泛应用于通信领域,为了探索不同生长温度对InN量子点的形貌影响,并且实现自组装InN量子点在1. 55μm通信波段的发光,对InN量子点的液滴外延及物性进行了相关研究。首先利用射频等离子体辅助分子束外延(PA-MBE)技术在GaN模板上,采用液滴外延方法在3种温度下生长了InN量子点结构。生长过程中靠反射高能电子衍射(RHEED)对样品进行原位监控。原子力显微镜(AFM)表征结果表明随着生长温度升高,量子点尺寸变大,密度减小。在生长温度350℃和400℃下,观测到了量子点;当温度高于450℃时,未观测到InN量子点。当生长温度为400℃时,量子点形貌最好,密度为6×10~8/cm^2,对400℃下生长的InN量子点进行了变温PL测试,成功得到InN量子点在1. 55μm波段附近的光致发光,并且随着测试温度的升高,量子点的发光峰位发生了先红移后蓝移最后又红移的S型曲线变化,这种量子点有望在未来应用于量子通信领域。

Because the 1.55μm band is widely used in the communication field,in order to explore the influence of different growth temperatures on the morphology of InN quantum dots(QDs),and to realize the 1.55μm luminescence of self-assembled InN QDs,the droplet epitaxy and physical properties of InN QDs were investigated.Firstly,the InN QDs structure was grown at three different temperatures by droplet epitaxy on a GaN template using radio frequency plasma-assisted molecular beam epitaxy(PA-MBE)technique.During the growth process,the sample was in-situ detected by RHEED.The AFM results show that the size of quantum dots increases and the density decreases with the growth temperature increasing.The InN QDs were observed at the growth temperatures of 350℃and 400℃.No InN quantum dots were observed at temperature 450℃.When the growth temperature is 400℃,the QDs have the best morphology and the QDs density is 6×108/cm2.The temperature dependent PL was measured on the sample grown at 400℃,and the 1.55μm emission from the InN QDs is successfully obtained.With the increase of measured temperature,the emission peaks of quantum dots have a S-curve change:from a red shift to a blue shift and last a red shift.These InN QDs are expected to be used in the quantum communication field in the future.