The basic monochromatic photovoltaic properties of a photodiode for laser power conversion

Abstract We studied the photovoltaic properties of a conventional silicon photodiode under monochromatic illumination conditions to clarify the loss mechanisms that are important for application as a laser power converter. While the short-circuit current increases linearly with the excitation power, the power dependence of the open-circuit voltage consists of two regions with different slopes as a result of a change in the non-radiative recombination process. At higher excitation power densities, thermal effects play a key role in the current–voltage characteristics, and therefore the maximum conversion efficiency is achieved at a certain excitation-power density. Furthermore, the optimum excitation wavelength shifts towards longer wavelengths as the excitation power density increases, because the optimum value is determined by a trade-off between the optical absorption strength and the excitation power density.