Kozak O. Photoelectric properties of multilayer heterostructures based on InGaAs alloys

The mechanisms of photoconductivity, photovoltage force and influence of defect levels in quantum dot solar cell are carefully studied. The role of deep layers on the photoelectric properties of vertical metamorphic InAs/In0.15Ga0.85As and pseudomorphic InAs/GaAs structures with quantum dots has been studied. In particular, in the case of an electrically active substrate, metamorphic and pseudomorphic nanostructures showed a bipolar photovoltage signal. In the presence of an electrically inactive substrate in combination with thick buffers, it strongly inhibits the effect of photoactive depth levels that occur on interfaces with the si-GaAs substrate on the photoelectric properties of nanostructures. It is shown that the spectrum of electron traps of metamorphic structures concentrated mainly around quantum dots is richer than in the pseudomorphic structure InGaAs / GaAs. Most defects have been identified as known complexes of point defects associated with GaAs and GaAs-In (Ga) As interfaces. The dependence of the defect density in metamorphic InAs / InxGa1–xAs on x is demonstrated. The influence of additional AlAs capping layers on quantum dots properties was investigated.