Ohmic contact and space-charge-limited current in molybdenum oxide modified devices

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• 作者：Zhaoyue Lü ; Zhenbo Deng ; Jianjie Zheng ; Ye Zou ; Zheng Chen ; Denghui Xu ; Yongsheng Wang
• 关键词：Ohmic contact ; Molybdenum oxide (MoO₃) ; Hole mobility ; Trap state
• 刊名：Physica E
• 出版年：2009
• 出版时间：October 2009
• 年：2009
• 卷：41
• 期：10
• 页码：1806-1809
• 全文大小：248 K

文摘

The effect of indium-tin oxide (ITO) surface treatment on hole injection of devices with molybdenum oxide (MoO₃) as a buffer layer on ITO was studied. The Ohmic contact is formed at the metal/organic interface due to high work function of MoO₃. Hence, the current is due to space charge limited when ITO is positively biased. The hole mobility of N, N′-bis-(1-napthyl)-N, N′-diphenyl-1, 1′biphenyl-4, 4′-diamine (NPB) at various thicknesses (100–400 nm) has been estimated by using space-charge-limited current measurements. The hole mobility of NPB, 1.09×10⁻⁵ cm²/V s at 100 nm is smaller than the value of 1.52×10⁻⁴ cm²/V s at 400 nm at 0.8 MV/cm, which is caused by the interfacial trap states restricted by the surface interaction. The mobility is hardly changed with NPB thickness for the effect of interfacial trap states on mobility which can be negligible when the thickness is more than 300 nm.