低温近场光学显微术对InGaN/GaN多量子阱电致发光温度特性的研究

Study of temperature dependent electroluminescence of InGaN/GaN multiple quantum wells using low temperature scanning near-field optical microscopy

使用实验室自制的低温近场光学显微镜研究了InGaN/GaN多量子阱发光二极管在室温和液氮温度下的近场光学像和近场光谱,发现随着温度的降低,不仅近场光学像的光强起伏大大减小,量子阱发光峰先蓝移后红移,而且在液氮温度下在光子能量更高的位置上出现了新的发光峰.通过对实验结果的分析,我们将这个新出现的峰归结为p-GaN层中导带底-受主能级间跃迁形成.

Though GaN based semiconductor materials and devices have achieved giant commercial success, there were few reports on their electroluminescent near-field optical studies at low temperature. In this paper we present our results of the electroluminescent near-field images and spectra at both room temperature and liquid nitrogen temperature by using a lab-made low temperature scanning near- field optical microscope. We found that with the decreasing of sample temperature, the fluctuation of electroluminescent intensity in the near-field images is reduced greatly and the peak photon energy of the spectra emitted from the quantum wells exhibits a blue-shift at first and then a red-shift. A new spectral peak emerges at higher photon energy at liquid nitrogen temperature. According to our analysis, this higher photon energy peak is attributed to the transition from the bottom of conduction band to the acceptor energy states in the p-GaN cap layer.