Effect of the charge-carrier drift in a built-in quasi-electric field on the emission spectrum of the graded-gap semiconductors

The shape of the band-to-band photoluminescence spectrum for a graded-gap semiconductor in conditions of nonequilibrium charge-carrier transport affected by a built-in quasi-electric field E=e−1∇Eg was calculated. It was demonstrated that the distortion of the short-wavelength region of the emission spectra occurs due to the coordinate dependence on the radiative recombination probability in the wide-gap region of the crystal. The calculations were confirmed by measuring the photoluminescence spectra for the AlxGa1−xAs undoped (n≤1016 cm−3) graded-gap solid solutions with E varying in the range of 90–650 V/cm at 300 K.