In this paper, heterojunction photodetector based on drop casting of colloidal multi-walled carbon nanotubes prepared by arc discharge technique on single crystalline silicon was demonstrated. The structural and optical of multiwalled carbon nanotubes MWCNTs was investigated by x-ray diffraction XRD, scanning electron microscopy SEM, Fourier transformation infrared spectroscopy FT-IR, and UV-vis spectroscopy. The dark current-voltage I -V characteristics revealed that MWCNTs/Si heterojunction showed a good rectification characteristics and the ideality factor was found to be around 3.1. The photocurrent to dark current ratio was 1.16 x 10(3) at 8V bias applied bias and light intensity of 100 mW/cm(2). The photodetector exhibited good linearity characteristics. The photodetector responsivity was estimated as 0.32 A/W at 800 nm at 9 V reverse bias. The open circuit voltage V-oc and short circuit current density J(SC) of the device were measured.The photodetector has rise time of 30 ns in absence of the external field. (C) 2018 Elsevier GmbH. All rights reserved.