T. Riedl et al., Injection lasers with vertically aligned InP/GaInP quantum dots: Dependence of the threshold current on temperature and dot size, APPL PHYS L, 73(25), 1998, pp. 3730-3732
We report on threefold-stacked vertically aligned InP/GaInP quantum dot inj
ection lasers emitting in the visible part of the spectrum (690-705 nm) wit
h a low threshold current density of j(th) = 172 A/cm(2) at 90 K showing a
thermally activated increase towards higher temperatures. We derived an act
ivation energy for this behavior, which is found to be just one half of the
energetic distance between the dot transition energy and the wetting layer
band gap. Thus, we identify thermal evaporation of carriers out of the dot
s and into the wetting layer states: as the process responsible for the inc
rease in the threshold current. The nonradiative carrier lifetime in the we
tting layer (tau(nr)(WL)) is estimated to be approximately 250-400 ps. (C)
1998 American Institute of Physics. [S0003-6951(98)02851-4].