The frequency dependence of capacitance of Schottky barriers on AlxGa1−xAs@B:Si shows evidence of the alloy broadening of the emission and capture rates of theDXcenter. The data are analyzed by assuming a Gaussian distribution for the emission and capture barriers of theDXcenter. The variation of the high‐frequency (1‐MHz) capacitance as a function of temperature suggests a temperature dependence of the ionization energy of theDXcenter that might arise from an entropy contribution to the ionization energy of theDXcenter as suggested by Theisetal. [Mater. Sci. Forum38–41, 1073 (1989)].