In this paper, we consider the issue of research and development of on-chip optoelectronic devices designed for the optical interconnecting of integrated circuit elements. We address the conceptual on-chip optical interconnections based on A<sup>III</sup>B<sup>V</sup> nanoheterostructure lasers with functionally integrated modulators of optical radiation. According to the estimations, these optoelectronic devices can generate subpicosecond optical pulses. The paper is aimed at the development of numerical models, simulation methods, and specialized software. These aids are intended for the research of physical processes taking place in high-speed heterostructure photodetectors suitable for operation as parts of on-chip optical interconnections together with the lasers-modulators. We propose to utilize the drift-diffusion approximation of the semiclassical approach for the numerical simulation of charge carrier transport and accumulation in semiconductor photosensitive heterostructures. The drift-diffusion numerical simulation technique was developed. This technique is based on the application of the Newton method, implicit difference scheme, and Slotboom drift-diffusion formulation in terms of electron and hole imref exponents and electrostatic potential. We researched p+<i>-Al<sub>0.3</sub>Ga<sub>0.7</sub>As/</i>i-<i>GaAs/</i>n+<i>-Al<sub>0.3</sub>Ga<sub>0.7</sub>As</i> and <i>metal</i>/n-<i>Al<sub>0.3</sub>Ga<sub>0.7</sub>As</i>/n+<i>-GaAs</i> heterostructures. Rise and fall times of the devices being considered are approximately equal and amount to about 1.6 ps for the p-i-n structure and 1.7 ps for the Schottky-barrier photodiode. We concluded that it is reasonable to develop the methods directed at the improvement of photodetector response speed.