Storage and transfer of optical excitation energy in GaInP epilayer: Photoluminescence signatures

Abstract

GaInP alloy could be the most trusted key material for fabricating super-high-efficiency single- and multi-junction solar cells, especially for space applications. The storage and transfer of optical excitation energy in this key alloy is thus a key subject of the energy conversion from optical to electrical. In this article we present a study of the subject through investigating photoluminescence (PL) degradation in the GaInP epilayer at 4 K under the continuous optical excitations of ultraviolet (UV) 325 nm, visible 488.0 and 514.5 nm lasers. It is found that the decline of PL intensity with the irradiation time may be represented by I(t)/I0=1+tτ−1−1+C, where I0 is the luminescence intensity at the beginning of irradiation, τ a time constant, and C a background. Moreover, the PL degradation degree reduces with increasing the excitation wavelength. In addition, some red shift of the PL peak is observed accompanying with the intensity decline under the UV laser excitation. These PL signatures indicate that the localized carriers within the local atomic ordering domains play a major role in the storage and transfer of the excitation energy via photon recycling processes.