PHOTODETECTOR WITH CONTROLLED RELOCATION: DRIFT-DIFFUSION MODEL AND APPLICATION IN OPTICAL INTERCONNECTIONS

Abstract

Previously, we proposed an injection laser with a double AIIIBV nanoheterostructure for the generation and modulation of light in optical interconnections for integrated circuits. To convert short optical pulses generated by the laser-modulator into electrical signals, a technologically compatible photodetector with subpicosecond response time is needed. Traditional designs of photosensitive semiconductor devices do not meet the specified requirements. Therefore, we developed a promising concept of a high-speed photodetector with controlled relocation of carrier density peaks within specially organized quantum regions. This optoelectronic device includes a longitudinal photosensitive p-i-n junction and a transverse control heterostructure, which containstwo low-temperature-grown layers and two control junctions. Before the trail of an optical pulse, the photodetector operates as a classical p-i-n photodiode. Transverse electric field is activated only during the back edge of a laser pulse. It relocates the peaks of electron and hole densities from the absorbing region to the regions with low carrier mobility and short lifetime. This process leads to the decrease in response time to a subpicosecond value. In our previous papers, we estimated the performance of the considered device using a quantum mechanical combined model that had not taken into account certain aspects of charge carrier transport in its structure. This paper is aimed at a proper semiclassical analysis of transients in the photodetector with controlled relocation by means of a two-dimensional drift-diffusion model. For the numerical implementation of the model, we develop a finite difference simulation technique based on the explicit method and applied software. According to the obtained results, it is reasonable to use the differential connection principle in order to compensate displacement currents in the supply circuit of the device. In view of this feature, we propose a circuit of optical receiver that provides the generation of resultant electrical signal as well as the required mode of the control voltage application to the photodetector contacts, and a driver circuit for the lasers-modulators.