arXiv subjects

Massimo V. Fischetti

Publications and source records attributed to Massimo V. Fischetti.

21 records · Page 2Linked to original sources

arXiv2012

Charged Impurity Scattering in Graphene Nanostructures

We study charged impurity scattering and static screening in a top-gated substrate-supported graphene nanostructure. Our model describes how boundary conditions can be incorporated into scattering, sheds light on the dielectric response of these nanostructures, provides insights into the effect of the top gate on impurity scattering, and predicts that the carrier mobility in such graphene heterostructures decreases with increasing top dielectric thickness and higher carrier density. An increase of up to almost 60 percent in carrier mobility in ultrathin top-gated graphene is predicted.

cond-mat.mes-hall↗

arXiv2012

Theory of Interfacial Plasmon-Phonon Scattering in Supported Graphene

One of the factors limiting electron mobility in supported graphene is remote phonon scattering. We formulate the theory of the coupling between graphene plasmon and substrate surface polar phonon (SPP) modes, and find that it leads to the formation of interfacial plasmon-phonon (IPP) modes, from which the phenomena of dynamic anti-screening and screening of remote phonons emerge. The remote phonon-limited mobilities for SiO$_{2}$, HfO$_{2}$, h-BN and Al$_{2}$O$_{3}$ substrates are computed using our theory. We find that h-BN yields the highest peak mobility, but in the practically useful high-density range the mobility in HfO$_{2}$-supported graphene is high, despite the fact that HfO$_{2}$ is a high-$κ$ dielectric with low-frequency modes. Our theory predicts that the strong temperature dependence of the total mobility effectively vanishes at very high carrier concentrations. The effects of polycrystallinity on IPP scattering are also discussed.

cond-mat.mes-hall↗

arXiv2011

Generalized phonon-assisted Zener tunneling in indirect semiconductors with non-uniform electric fields : a rigorous approach

A general framework to calculate the Zener current in an indirect semiconductor with an externally applied potential is provided. Assuming a parabolic valence and conduction band dispersion, the semiconductor is in equilibrium in the presence of the external field as long as the electronphonon interaction is absent. The linear response to the electron-phonon interaction results in a non-equilibrium system. The Zener tunneling current is calculated from the number of electrons making the transition from valence to conduction band per unit time. A convenient expression based on the single particle spectral functions is provided, enabling the numerical calculation of the Zener current under any three-dimensional potential profile. For a one dimensional potential profile an analytical expression is obtained for the current in a bulk semiconductor, a semiconductor under uniform field and a semiconductor under a non-uniform field using the WKB (Wentzel-Kramers-Brillouin) approximation. The obtained results agree with the Kane result in the low field limit. A numerical example for abrupt p - n diodes with different doping concentrations is given, from which it can be seen that the uniform field model is a better approximation than the WKB model but a direct numerical treatment is required for low bias conditions.

cond-mat.mes-hall↗