Thermal characteristics of 1.3um InAs-based quantum-dot lasers on silicon substrates (Conference Presentation)

We investigate the temperature and pressure dependence of a series of intrinsic and modulation p-doped InAs-based dot-in-well (DWELL) laser diodes grown on silicon substrates. Temperature dependence of the threshold current density (Jth) and pure spontaneous emission spectra provide an insight into inhomogeneity and non-radiative recombination mechanisms within the devices. Initial investigations showed that the intrinsic devices exhibited low temperature sensitivity in the range 170-200K. Above this, Jth increased more rapidly consistent with Auger recombination. P-doping increased the temperature at which Jth(T) started to increase up to 300K with a temperature insensitive region close to room temperature. P-doping delays the onset of carrier thermalization, leading to a high T0 but with an associated higher Jth. Temperature dependence of gain spectrum broadening was investigated by measuring the spontaneous emission spectral width parameter (1/e2) just below Jth (T). A strong direct correlation is found between the temperature dependence of peak width with the temperature dependence the radiative component of threshold, Jrad(T). At low temperature the correlation is consistent with strong inhomogeneous broadening of the carrier distribution. As temperature increases Jth reduces associated with carriers thermalizing to lower energy states. At higher temperatures homogeneous thermal broadening coupled with non-radiative recombination causes Jth to increase. Inhomogeneous broadening is more pronounced in the p-doped devices due to coulombic attraction between acceptor holes and injected electrons. A detailed analysis of recombination processes using high hydrostatic pressure and spontaneous emission in these lasers as a function of doping density will be presented and discussed at the conference.