Radiative recombination in heavily doped n-AlxGa1_xAs-p-GaAs heterojunctions

Heavily doped n-AlxGa1_xAs-p-GaAs heterojunctions prepared by liquid phase epitaxy have been investigated. At high bias (U > 1.40 V at 77 °K), the emission of the diodes for which the “tip” temperature has been 850 °C corresponds to a band-acceptor transition in GaAs. The emission spectrum of the diodes for which the “tip” temperature has been equal or higher than 870 °C shows the existence of a peak-shifting line. In order to explain the peculiarities of the emission spectra a “band filling” mechanism involving a conduction band tail formed as a consequence of the impurity interdiffusion is discussed.