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While boron nitride (BN) substrates have been utilized to achieve high electronic mobilities in graphene field effect transistors, it is unclear how other layered two dimensional (2D) crystals influence the electronic performance of graphene. In this Letter, we study the surface morphology of 2D BN, gallium selenide (GaSe), and transition metal dichalcogenides (tungsten disulfide (WS 2) and molybdenum disulfide (MoS 2)) crystals and their influence on graphene's electronic quality. Atomic force microscopy analysis shows that these crystals have improved surface roughness (root mean square value of only∼ 0.1 nm) compared to conventional SiO 2 substrate. While our results confirm that graphene devices exhibit very high electronic mobility (μ) on BN substrates, graphene devices on WS 2 substrates (G/WS 2) are equally promising for high quality electronic transport (μ∼ 38 000 cm 2/V s at room temperature …