Characteristic temperature coefficients of the threshold current (T0) and the external quantum efficiency (T1), on highly-strained In0.35Ga0.65As- ((lambda) =1.17micrometers ) and In0.4Ga0.6As- ((lambda) =1.19micrometers ) QW lasers, are studied as simple functions of the temperature dependent of the physical parameters of the semiconductor lasers. Simple expressions of characteristics temperature coefficients of the threshold current (T0) and the external differential quantum efficiency (T1) are expressed as functions as physical parameters and their temperature dependencies. The parameters studied here include the threshold (Jth) and transparency (Jtr) current density, the carrier injection efficiency (Ninj) and external (Nd) differential quantum efficiency, the internal loss ((alpha) i), and the material gain parameter (G0). Simple expressions for T0 and T1 are derived in terms of the fundamental device parameters, indicating that the observed cavity length dependence is due to the length dependence of the modal threshold gain. The influence of monomolecular, radiative, and Auger recombination on the characteristic temperature of the transparency current density, Ttr, are analyzed. A measurement of Ttr, then allows one to determine the dominant recombination mechanisms in the QW. The characteristic temperature of the internal loss, T(alpha i), can be used to determine the influence of intervalence band absorption on the value of T0. The analysis done on the InGaAs QW lasers show that the simple expressions for T0 and T1 values gives consistent results between experiments and theory.