Effect of Built-in Electric Field on Miniband Structure and Carrier Nonradiative Recombination in InGaAs/GaAsP Superlattice Investigated Using Photoreflectance and Photoluminescence Spectroscopy

We investigated the effect of built-in electric field on miniband formation and carrier nonradiative recombination in a superlattice structure by using photoreflectance (PR) and photoluminescence (PL) spectroscopy for a strain-balanced InGaAs/GaAsP superlattice inserted in p-i-n GaAs solar cell and n-n GaAs structures. Two critical energies were obtained in the PR spectra, which corresponded to the energy differences between the Γ and π points in the mini-Brillouin zone of the first electron level and the first heavy hole level. The obtained miniband widths of both samples were same, which were smaller than the calculated values by using a flat-band structure model without a built-in electric field. From these results, it was deduced that the built-in electric field does not affect the miniband width. The PL signal intensity of the p-i-n structure samples did not change, whereas that of the n-n structure samples decreased with decreasing barrier thickness. We concluded that the radiative recombination probability decreases and the non-radiative recombination probability increases due to miniband formation.