IEEE Nano 2012 – Heat Transfer in Nanoelectronics by Quantum Mechanics

Aug. 27, 2012 - PRLog -- Background

Heat transfer began with classical physics. Theories of Einstein and Debye identified phonons as the heat carriers in Fourier’s heat conduction equation. Since then, heat transfer by phonons has served well in deriving the thermal response of macroscopic bodies. However, unphysical findings for the thermal response of nanostructures show classical heat transfer needs to be modified, e.g., for a vanishing heat capacity of the atom as required by QM in combination with the conservation of Joule heat by up-conversion to the TIR resonance of the nanostructure by QED. QM stands for quantum mechanics, TIR for total reflection, and QED for quantum electrodynamics.
With these modifications, charge is created in conserving Joule heat instead of by an increase in temperature. In this regard, IEEE Nano 2012 on nanoelectronics included numerous discussions of QM in relation to classical physics for memristors, the Ovshinsky Effect, 1/f noise, the Landauer effect, and heat dissipation in nanocomputing. See http://www.nanoqed.org at “IEEE Nano 2012,” Paper and Presentation, 2012.

Summary of Discussions

Memristors The Hewlett-Packard claim that oxygen vacancies are the source of positive charged holes in memristors is unlikely because memristor behavior is observed in materials without oxygen vacancies. Indeed, space charge is thought to provide the positive holes in gold and silicon nanowires, but a source of space charge is not identified.  In contrast, QED conserves Joule heat by creating photons within the memristor that by the photelectric effect produce their own space charge. Simulations display memristor hysteresis behaviour without fitting parameters. Ibid

The Ovshinsky Effect Ovshinsky always thought the resistance of GST films in PCRAM devices changed by the redistribution of charge carriers. Based on classical physics, PCRAM research today claims resistance changes because the GST crystalline state is transformed to the amorphous state by melting. QM asserts the heat capacity of submicron GST films vanishes, and therefore melting does not occur. Instead, QED conserves Joule heat by creating charge in the submicron GST film that produces the resistance change. Consistent with Ovshinsky, simulations show how resistance changes with GST film thickness. Ibid

1/f Noise The classical Hooge relation that claims 1/f noise is caused by collisions of free electrons with the crystal lattice is unlikely because the residence time of the electron in nanoelectronic circuit elements is too short to produce low frequency noise.  Instead, QM asserts Joule heat cannot be conserved by an increase in temperature, and therefore conservation proceeds by the QED creation of photons within the circuit element, the QED photons producing excitons by the photoelectric effect.  In nanowires, QM creates a step change in charge giving a step in current that for a constant voltage gives a step in power, the Fourier transform of which gives the 1/f noise spectrum. Noise in nanoelectronics is caused by a relatively small number of positively charged holes and not by the Hooge relation based on a large number of free electrons. Ibid

Landauer Limit  The classical long-standing Landauer limit gives the minimum possible amount of thermal energy required to erase one bit of information from memory as kT * ln 2. But QM requires kT to vanish in nanoelectroncs, and therefore no heat is dissipated in erasing memory. However, QM requires the creation of charge that generates 1/f noise that may be more restrictive than the cost of erasure in that the performance of the nanoelectronics may be significantly degraded. Ibid      

Heat Dissipation in Computing Classical heat transfer shows Joule heating limits nanoelectronics because of damage from high temperatures. By QM, thermal damage is not expected as the heat capacity of atoms in nanoelectronics vanishes. However, it is important that all circuit elements including interconnects are submicron, as otherwise thermal damage will definitely occur. Ibid  

Subwavelength Focusing Maxwell’s equations based on classical physics rely on the fluctuation dissipation theorem (FDT) to correlate temperatures with dipole oscillations. But classical physics always assumes the atom has heat capacity, and therefore the temperatures in surfaces of subwavelength focusing separated by nanoscale dimensions are implicitly assumed to satisfy the FDT.  In contrast, QM precludes the atom under EM confinement at the nanoscale from having the heat capacity required to produce the temperature fluctuations necessary to satisfy the FDT. Maxwell solutions of subwavelength focusing are therefore questionable.

X-ray Irradiation of Nanoparticles  Irradiation of nanoparticles (NPs) by X-rays is thought to cause surface strains and distortions from increases in temperature by Joule heating. But this is unlikely because QM precludes the NPs from temperature increases in conserving absorbed X-rays. Instead, QED photons are created that charge the NPs and distort the NPs by electrostatic repulsion.

Nanowire Vibration Vibration models of nanowires as Timoshenko beams showing increased resonant frequencies are thought caused by surface stresses from high surface-to-volume ratio (SVR) of nanowires. Uncoordinated surface atoms are claimed to be the source of surface stress, but the mechanism by which the high SVR is related to the surface stress is not identified. In contrast, QM asserts the high SVR in nanowires creates QED photons in the circumferential TIR mode of the wire that places the wire material in hydrostatic compression. The EM energy creating the QED photons is the heat from the supports holding the nanowire ends during mechanical tests. Dissipative strain hardening energy is negligible. The hydrostatic compression is not permanent, but temporary occurring only during the time the nanowire is absorbing thermal energy from the supports. Since QM precludes any increase in wire temperature, the high SVR conserves the thermal energy from the supports by creating QED photons that creates charge by the photoelectric effect, the hydrostatic compression produced by charge repulsion.   Both the yield stress and elastic modulus of the nanowire are enhanced above bulk because the compressive stress state must be overcome before yielding may begin. Simulations to confirm the QM enhancement of yield and modulus under hydrostatic compression are in progress.

IR Antenna Measurement of IR temperature are proposed by placing an antenna of a nanowire on a substrate. Although the length of the antenna matches the IR half-wavelength, QM requires the temperature of the nanowire itself to not change, and therefore what is being measured is that of the substrate. If the nanowire is freely suspended above the substrate, QM predicts there is no increase in temperature, thereby negating IR temperature measurements.  

Organ Pipes Nanoscale organ pipes are not likely to produce acoustic waves, although sound may be produced in thermophones of nanowires. However, QM and not classical physics explains thermophones at the nanoscale. Classically, sound is produced in micron size wires by thermal vibrations of the wire surface, but laser measurements cannot detect surface vibration in nanoscale thermophones. By QM, QED radiation is emitted by the nanowires with sound produced upon the absorption of the QED radiation in the surrounding air. See http://www.prlog.org/10553668-nanotrumpets-produce-sound-...

Conclusions

1. QM and not classical physics is applicable to the dissipation of Joule heat transfer in nanoelectroncs.

2. QED induced radiation relying on a vanishing heat capacity of the atom by QM avoids unphysical explanations of nanoscale observation based on classical physics.