Effect of underlying boron nitride thickness on photocurrent response in molybdenum disulfide - Boron nitride heterostructures

Here we report on the photocurrent response of two-dimensional (2D) heterostructures of sputtered MoS₂ on boron nitride (BN) deposited on (001)-oriented Si substrates. The steady state photocurrent (I_ph) measurements used a continuous laser of λ = 658 nm (E = 1.88 eV) over a broad range of laser intensities, P (∼1 μW < P < 10 μW), and indicate that I_ph obtained from MoS₂ layers with the 80 nm BN under layer was ∼4 times higher than that obtained from MoS₂ layers with the 30 nm BN under layer. We also found super linear dependence of I_ph on P (I_ph ∝ P^γ, with γ > 1) in both the samples. The responsivities obtained over the range of laser intensity studied were in the order of mA/W (∼12 and ∼2.7 mA/W with 80 nm BN and 30 nm BN under layers, respectively). These investigations provide crucial insight into the optical activity of MoS₂ on BN, which could be useful for developing a variety of optoelectronic applications with MoS₂ or other 2D transition metal dichalcogenide heterostructures.