The Effect of Surface Energy on Atomic Layer Deposited Al2O3 Dielectric on MoS2 crystals

Wednesday, 27 May 2015
Salon C (Hilton Chicago)
S. Park, H. Lee, Y. Choi, and W. Choi (Kookmin University)
Molybdenum disulfide (MoS2) is a promising two-dimensional semiconductor for thin-film transistors (TFTs) because of the high field-effect mobility, low subthreshold swing, and high on/off ratio. For the fabrication of high-performance MoS2 TFTs, it is essential to integrate a high dielectric constant (high-k) gate insulator such as HfO2 or Al2O3 on MoS2. However, the absence of dangling bonds or functional groups on MoS2 basal plane often requires the pretreatment of MoS2 surface by O2 plasma or ultraviolet (UV)-O3, which will inevitably influence the surface energy. In this presentation, we report a systematic investigation on the effect of MoS2 surface energy on the atomic layer deposited (ALD) Al2O3. We correlate the surface coverage and morphology of ALD Al2O3 dielectric with the MoS2 surface energy based on the measurement with scanning electron microscopy (SEM), atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. We also provide electrical properties of functionalized Al2O3/MoS2 interface with current-voltage (I-V) and capacitance-voltage (C-V) characteristics.