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We investigate the n-ZnO/p-Si heterojunction photodiodes which were fabricated by pulsed laser deposition of ZnO films on p-Si substrate. A ZnO thin layer deposited at 200°C in oxygen free ambient was used as a buffer layer for the subsequent ZnO growth. The influence of ZnO homobuffer layer on n-ZnO/p-Si photodiode was studied. The results obtained by X-ray diffraction and atomic force microscopy showed that ZnO film with a homobuffer layer had better crystallinity and a smoother surface than the film without the buffer layer. As characterised by current–voltage (I–V) measurements, the dark leakage current of the buffered sample decreased significantly. Under Xe arc lamp illumination of 670 nm, photoresponsivity of 028 A W–1 and quantum efficiency of 48% at 5 V reverse bias were obtained from the photodiode with ZnO homobuffer layer. [ABSTRACT FROM AUTHOR]