Dynamics of the permittivity of a semiconductor acted on by a femtosecond laser

Ultrafast electron transfer through a silicon–vacuum interface induced by the action of an intense femtosecond laser pulse

“…Figure 4 shows the dependences of the concentrations of electrons and holes, as well as the electric field strength, on the distance to the surface at the moment of time corresponding to the trailing edge of the pulse (t = t′ + t 0 ) with energy density Q 0 = 0.5 J cm −2 (t p = 100 fs), which is higher than the silicon damage threshold. At such fluence, according to [46] (for λ ~ 800 nm), large-scale periodic structures oriented parallel to the electric field vector of the femtosecond pulse begin to form, which, according to the hypothesis of the authors of [18][19][20][21], is related to the formation of a waveguide structure by depletion of electrons in the surface layer of the semiconductor. As can be seen from the figure, the size of the layer in which the excess positive charge is mainly localized, l + , does not exceed 3-4 nm.…”

“…The second effect associated with electron emission has been less widely discussed in the scientific literature, but also deserves close attention. Shandybina et al [18][19][20][21] put forward the hypothesis that strong electron emission may be responsible for the formation of surface periodic structures on silicon oriented parallel to the radiation polarization vector. The idea is as follows.…”

“…In this case, it is usually assumed that the maximum concentration of photoexcited carriers is localized on the surface. According to the authors of [18][19][20][21], the presence of a strong external electron emission will lead to the formation of a layer depleted of carriers (electrons) on the surface, and the concentration distribution maximum will be localized at a certain depth. Thus, an optically layered structure (air/depleted layer/metallized layer) is formed, which can play the role of a dynamic waveguide.…”

Picosecond laser structuring of monocrystalline silicon surface

“…Evaluations were performed with the diffusion, emission flows, temporal pulse shape of the dome taking into account for three models of semiconductor photo-excitation: models of two-photon excitation [11][12] ( fig. 4), the model of single-photon excitation, (Fig.…”

Excitation relaxation in the electron subsystem of a metal when it is irradiated with ultrashort laser pulses

“…It is shown in Ref. 4 that emission processes play an important role in the formation of periodic structures on the surface of a semiconductor when it is irradiated with powerful femtosecond pulses. Instantaneous thermalization of the nonequilibrium electrons was assumed when emission was taken into account, and this also requires additional verification.…”