Nonlinear photoluminescence of graded-gap AlxGa1−x As solid solutions

Abstract

Dependences of photoluminescence (PL) intensity for undoped and doped graded-gap AlxGa1−x As (x≲0.36) solid solutions on the excitation level J (1019 photon cm−2 s−1≲J≲1022 photon cm−2 s−1) were investigated for various built-in electric fields E=e −1▽E g (85 V/cm≲E≲700 V/cm). It was found that the accelerating effect of the field E gives rise to a complex dependence of intensity of the edge PL (I) on the excitation level. The nonlinearity of the I(J) dependence is attributed to the contribution of the two-photon absorption of PL emission when the latter is reemitted. An optimal range of E values exists (120 V/cm≲E≲200 V/cm). In this range, the contribution of two-photon absorption to the reemission process in undoped solid solutions is largest.