Effect of surface treatment of GaN based light emitting diode wafers on the leakage current of light emitting diode devices |
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Authors: | Wang Liang-Ji Zhang Shu-Ming Zhu Ji-Hong ZhuJian-Jun Zhao De-Gang Liu Zong-Shun Jiang De-Sheng WangYu-Tian and Yang Hui |
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Institution: | State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China; Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215125, China |
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Abstract: | To form low-resistance Ohmic contact to p-type GaN,
InGaN/GaN multiple quantum well light emitting diode wafers are
treated with boiled aqua regia prior to Ni/Au (5~nm/5~nm) film
deposition. The surface morphology of wafers and the current--voltage
characteristics of fabricated light emitting diode devices are
investigated. It is shown that surface treatment with boiled
aqua regia could effectively remove oxide from the surface of the p-GaN
layer, and reveal defect-pits whose density is almost the same as
the screw dislocation density estimated by x-ray rocking curve
measurement. It suggests that the metal atoms of the Ni/Au transparent
electrode of light emitting diode devices may diffuse into the p-GaN
layer along threading dislocation lines and form additional leakage
current channels. Therefore, the surface treatment time with boiled
aqua regia should not be too long so as to avoid the increase of
threading dislocation-induced leakage current and the degradation of
electrical properties of light emitting diodes. |
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Keywords: | GaN light emitting diode surface treatment leakage current |
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