In this paper we report the performance and study of GaAsAlGaAs (SCH) laser. The structures were grown by a new variant of the LPE‐technique with temperatures regimes lower than 600 °C. The Low Temperature LPE‐technique, recently propoused by ANDREEV and coworkers at the IOFFE‐Physico‐Technical Institute exhibit growth rates of the growing layers as low as that corresponding to MBE or MOCVD techniques. In this way, it is possible to obtain and control layer thicknesses in the structure of the order of tens to hundreds of Ångströms. Laser heterostructures with active layer thickness of 30 nm, were performed and the lowest threshold current density of 437 A/cm² for a cavity length of 1.33 mm were obtained. A typical growth process is described and a SEM structure microphotograph is shown. The dependences of the threshold current density J_th and the differential quantum efficiency η_d with the cavity length L are reported. From these data, other laser parameters are evaluated such as internal optical losses α₁, internal quantum efficiency η_i and the dependence of the maximum of the gain factor against the nominal current density J_nom at threshold. This dependence was compared with the theoretical predictions and a good agreement was found.