SelfHeating Effects in Nanowire Transistors (original) (raw)
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Modeling self-heating effects in 10nm channel length nanowire transistors
2010 Silicon Nanoelectronics Workshop, 2010
We investigate the role of self-heating effects on the electrical characteristics of a silicon nanowire transistor using a 3-D Monte Carlo device simulator that includes self-consistent solution of the energy balance equations for both acoustic and optical phonons. We find that self-heating effects in the nanowire transistor lead to more than 10.35 % degradation in the ON-current for V G =V D =1 V.
The role of the source and drain contacts on self-heating effect in nanowire transistors
2010
We find that self-heating effects are not pronounced in silicon nanowire transistors with channel length 10 nm even in the presence of the wrap-around oxide. We observe a maximum current degradation of 6% for V G = V D = 1.0 V in a structure in which the metal gates are far away from the channel. The overall small current degradation is attributed to the significant velocity overshoot effect in these structures. The lattice temperature profile shows moderate temperature rise and velocity of the carriers is slightly deteriorated due to self-heating effects when compared to isothermal simulations.
Modeling Thermal Effects in Nanodevices
IEEE Transactions on Electron Devices, 2000
In order to investigate the role of self-heating effects on the electrical characteristics of nanoscale devices, we implemented a 2-D Monte Carlo device simulator that includes the self-consistent solution of the energy balance equations for both acoustic and optical phonons. The acoustic and optical phonon temperatures are fed back into the electron transport solver through temperature-dependent scattering tables. The electrothermal device simulator was used in the study of different generations of nanoscale fully depleted silicon-on-insulator devices that are either already in production or will be fabricated in the next five to ten years. We find less degradation due to self-heating in very short channel device structures due to the increasing role of nonstationary velocity-overshoot effects which are less sensitive to the local temperature.
Self-Consistent Simulation of Heating Effects in Nanoscale Devices
2009 13th International Workshop on Computational Electronics, 2009
In this paper we present state of the art modeling of coupled electron-phonon transport in nanoscale CMOS SOI devices, in order to elucidate from a microscopic standpoint the role of device dimensions, boundary conditions and various material strategies on self-heating in this technology.
Thermal simulation techniques for nanoscale transistors
ICCAD-2005. IEEE/ACM International Conference on Computer-Aided Design, 2005.
Thermal simulations are important for advanced electronic systems at multiple length scales. A major challenge involves electrothermal phenomena within nanoscale transistors, which exhibit nearly ballistic transport both for electrons and phonons. The thermal device behavior can influence both the mobility and the leakage currents. We discuss recent advances in modeling coupled electronphonon transport in future nanoscale transistors. The solution techniques involve solving the Boltzmann Transport Equation (BTE) for both electrons and phonons. We present a practical method for coupling an electron Monte Carlo simulation with an analytic "splitflux" form of the phonon BTE. We use this approach to model selfheating in a 20 nm quasi-ballistic n+/n/n+ silicon diode, and to investigate the role of hot electron and hot phonon transport. 0-7803-9254-X/05/$20.00 ©2005 IEEE.
Numerical simulation of transient phonon heat transfer in silicon nanowires and nanofilms
Journal of Physics: Conference Series, 2007
This work proposes a numerical simulation of heat conduction in silicon nanowires and nanofilms. Boltzmann equation for phonons is solved in the relaxation time approximation. The equation is integrated in an axisymmetric cylindrical two dimensional geometry. Solid angle integration is done by means of Discrete Ordinate Method. Moreover, in contrast to other models published in literature, spectral dependency of relaxation times and acoustic wave dispersion are taken into account in this numerical resolution. Consequently, thermal profiles are obtained for silicon nanowires and nanofilms in steady state allowing computation of thermal conductivity and/or thermal conductance. Besides, we solve the unsteady Boltzmann equation in order to obtain nanosystems temporal evolution. The results obtained with this code match nanofilms and nanowires already predicted thermal profiles in steady state. In unsteady condition, diffusive state (Fourier) is discussed for nanowires and nanofilms. At low temperatures, ballistic phenomenons are seen in nanofilms, whereas, in nanowires, due to boundary scattering, diffusion regime is observed.
Current progress in modeling self-heating effects in FD SOI devices and nanowire transistors
Journal of Computational Electronics, 2012
In this paper we summarize 6 years of work on modeling self-heating effects in nano-scale devices at Arizona State University (ASU). We first describe the key features of the electro-thermal Monte Carlo device simulator (the two-dimensional and the three-dimensional version of the tool) and then we present series of representative simulation results that clearly illustrate the importance of selfheating in larger nanoscale devices made in silicon on insulator technology (SOI). Our simulation results also show that in the smallest devices considered the heat is in the contacts, not in the active channel region of the device. Therefore, integrated circuits get hotter due to larger density of devices but the device performance is only slightly degraded at the smallest device size. This is because of two factors: pronounced velocity overshoot effect and smaller thermal resistance of the buried oxide layer. Efficient removal of heat from the metal contacts is still an unsolved problem and can lead to a variety of non-desirable effects, including electromigration. We propose ways how heat can be effectively removed from the device by using silicon on diamond and silicon on AlN technologies. We also study the interplay of Coulomb interactions due to the presence of a random trap at the source end of the channel and the self-heating effects. We illustrate the influence of a positive and a negative trap on the magnitude of the on-current and the role of the potential barrier at the source end of the channel.
Atomistic simulations of heat transport in real-scale silicon nanowire devices
Applied Physics Letters, 2012
Utilizing atomistic lattice dynamics and scattering theory, we study thermal transport in nanodevices made of 10 nm thick silicon nanowires, from 10 to 100 nm long, sandwiched between two bulk reservoirs. We find that thermal transport in devices differs significantly from that of suspended extended nanowires, due to phonon scattering at the contact interfaces. We show that thermal conductance and the phonon transport regime can be tuned from ballistic to diffusive by varying the surface roughness of the nanowires and their length. In devices containing short crystalline wires phonon tunneling occurs and enhances the conductance beyond that of single contacts.
International Journal of Heat and Mass Transfer, 2011
Nanoscale phonon transport within silicon structures subjected to internal heat generation was explored. A Monte Carlo simulation was used. The simulation procedures differed from the current existing methods in which phonons below a predefined ''reference temperature'' were not accounted to reduce memory storage and computational resources. Results indicated that the heat diffusion equation significantly underestimates temperature distribution at nanoscales in the presence of an external heat source. Discussions on temperature distribution inside silicon thin film when heated by a pulsed laser, an electron beam or due to near-field thermal radiation effects were also provided.