Molecular-beam epitaxy of GaAs/Si(001) structures for high-performance tandem A III B V/Si-solar energy converters on an active silicon substrate

Abstract

In the present study, a method of low-temperature atomic layer epitaxy of GaAs at the initial stage of formation of a GaAs/Si heterojunction is used for growing GaAs films with a low density of threading defects. It was shown that growth of GaAs films can take place bypassing the stage of formation of islands, provided the first monolayer of GaAs is formed by atomic layer epitaxy at low temperature (200–350°C). A regime was found for growing the GaAs/Si films with a density of threading dislocations less than 106 cm–2, which corresponds to the best world achievements. In this mode, the GaAs/Si and Al0.2Ga0.8As/Si structures were grown for solar-energy converters, the devices were produced, and their characteristics were measured. It is shown that during the growth of the GaAs/Si heterojunction, a p–n-junction is formed in the near-surface layer of silicon. This allows one to produce high-performance cascade converters of solar energy based on the A III B V compounds on the active Si substrate in a single growth cycle.