In this study, the main electrical parameters, such as doping concentration (N-D), barrier height (Phi(CV)). depletion layer width (W-D), series resistance (R-s) and Fermi energy level (E-F), of GaAs/AlxGa1-xAs single quantum well (SQW) laser diodes were investigated using the admittance spectroscopy (C-V and G/omega-V) method in the temperature range of 80-360 K. The reverse bias C-2 vs. V plots gives a straight line in a wide voltage region, especially in weak inversion region. The values of Phi(CV) at the absolute temperature (T = 0 K) and the temperature coefficient (alpha) of barrier height were found as 1.22 eV and -8.65 x 10(-4) eV/K, respectively. This value of alpha is in a close agreement with alpha of GaAs band gap (-5.45 x 10(-4) eV/K). Experimental results show that the capacitance-voltage (C-V) and conductance-voltage (G/omega-V) characteristics of the diode are affected by not only temperature but also R-s. The capacitance-voltage-temperature (C-V-T) and conductance-voltage-temperature (G/omega-V-T) characteristics confirmed that temperature and R-s of the diode have effects on the electronic parameters in SQW laser diodes. (C) 2010 Elsevier B.V. All rights reserved.