  We explore the possibility to excite the so-called embedded solitons in
specially designed slot waveguides based on silicon and silica or silicon
nanocrystals. This requires the excitation of the structure with quasi-TM
polarized pulses -- for which Raman effect is absent -- and at a specific
infrared wavelength for which only the second- and fourth-order group velocity
coefficients are non-vanishing. Pulses launched in these conditions will
generate a spectrally localized continuum, associated to a frequency comb
coming from the spectral interference of many embedded solitons.
