Voltage transients due to the thermal electron capture and emission of DX centers in n-type Sn-doped Al0.26Ga0.74As were measured by the constant capacitance technique and transformed by Laplace defect spectroscopy (LDS). By analyzing the variations of discrete emission rates with different capture periods, corresponding relations between discrete capture and emission rates and capture coefficients were determined. The fine structures of electron capture barriers of the Sn-related DX centers were obtained by linear fitting the data of temperature-dependences of the capture coefficients. The results calcuated by using the first principle pseudopotential method show that the fine structures of the capture barriers mainly contribute to Al/Ga at different local configurations near Sri atoms due to the alloy random effect
