The ultimate target for silicon photonics is to merge together all electronic and photonic functions on the same CMOS platform. This requires efficient light emitters and absorbers directly integrated on silicon chips, the lack of which presently forms one of the major bottlenecks for further progress. In this work, a possible solution is presented where diffusion-driven charge transport (DDCT), lateral doping of silicon, and III-V nanowire growth are combined to create fully integrated near-surface light emitters and absorbers controlled solely by biasing the underlying silicon wafer. According to the three-dimensional full-device simulations carried out in this paper, DDCT enables high efficiencies for both light emission and photodiode operation in technically feasible silicon-integrated free-standing nanowire structures. Moreover, the results indicate that DDCT is especially well suited for the commonly used 1.55 μm wavelength due to the optimal band-gap difference with silicon, which promotes both a high injection efficiency and low voltage losses.