We present in this work the first monolithic integration of a 111, V resonant tunnelling diode (RTD) on an exactly (001)-oriented Si substrate, The crystalline quality of the InP starting layer and that of the RTD was determined by high-resolution X-ray diffractometry (HRXRD). A 2mum InP starting layer on a Si substrate exhibited a FWHM HRXRD layer peak intensity of 90 arcsec, The layer stack on Si accurately matched the same layer stack grown on an InP substrate. This demonstrated the high potential of this approach. Room temperature DC measurements of RTD structures exhibited a negative differential resistance at a high peak current density of 6 x 10(4) A/cm(2). (C) 2002 Elsevier Science B.V. All rights reserved.