Characteristics of GaAsAlGaAs (SCH) lasers grown by low‐temperature LPE technique

Abstract

AbstractIn 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 Jth and the differential quantum efficiency ηd with the cavity length L are reported. From these data, other laser parameters are evaluated such as internal optical losses α1, internal quantum efficiency ηi and the dependence of the maximum of the gain factor against the nominal current density Jnom at threshold. This dependence was compared with the theoretical predictions and a good agreement was found.