Quasi-one-dimensional polaron gas in a GaAs quantum wire
In this work we present a study of the plasmon-longitudinal-optical (LO) phonon collective excitation as a function of the quasi-one-dimensional wave vector for several electronic densities and thickness of the wires. We observed that the intra- and intersubband excitation collective energies are very sensitive to electronic density variation. This effect is more pronounced for the lower branch of the collective excitation energy and for narrower wires. Our calculations are performed using the Singwi, Tosi, Land and Sjolander (STLS) theory, at zero temperature, assuming a three-subband model, where only the first subband is occupied by electrons.
Polaronic effects on the collective excitation energies in a quantum wire
In this work we report a investigation of the plasmon-longitudinal-optical (LO) phonon interaction effects on the intersubband and intrasubband collective excitation energies in a GaAs-AlνGa1-νAs rectangular quantum well wire. We observe a resonant split of the collective excitation energy into two branches, one with energy lower and other with energy higher than the LO-optical phonon energy ℏωLO. Our calculations are performed using a self-consistent field approximation, which includes the local-field correction within the Singwi, Tosi, Land, and Sjolander (STLS) theory at zero temperature and assuming a three-subband model, where only the first subband is occupied by electrons. The potential confining effects on the collective energies were also considered.
Clustering phenomena in low-pressure reactive plasmas. Basis and applications
Abstract Clustering phenomena of particles below a few nm in size in low-pressure reactive plasmas have been studied in capacitively coupled high-frequency SiH4 discharges. Clusters nucleate around a size of 0.5 nm, Si4Hx and subsequently grow due to influxes of SinHx (1 < n < 4) and other molecular species. Because of long gas-residence time and small surface loss-probability of clusters, even neutral ones accumulate to nucleate in the reactor. Appearance of negatively charged clusters is considered to become noticeable at around Si4Hx. The growth of clusters is suppressed by using thermophoretic force, gas flow, periodical discharge modulation, and hydrogen dilution. The reactor has been newly developed to suppress the growth of clusters both by thermophoretic force and by gas flow and evacuation without stagnation. Using the reactor, a-Si:H films of extremely high quality have been successfully deposited.