ამირან ბიბილაშვილი

The results of investigation of the residual photomechanical effect (PME) in a monocrystalline n-Si sample at various temperatures by the method of microindentation following exposure to light are considered. It is shown that a decrease in the residual PME is an exponential function of time and temperature.

Requirements for cooling and power consumption in space platforms are subject to significantly greater constraints than the requirements for terrestrial applications. Existing cooling systems incorporate various mechanisms including thermoelectric (Peltier) cooling elements, radiative cooling, and phase‐change compressor‐based systems. This paper outlines an alternative mechanism currently in development called “thermotunneling”. This mechanism exploits electron tunneling across a vacuum gap of ∼10nm to effect a temperature differential with high efficiency. When complete, these devices (“Cool Chips”) are expected to offer a compact, lightweight, low maintenance and highly efficient (in excess of 50% of Carnot Efficiency) thermal management solution ideally suited for the needs of aerospace applications. This article was originally published with an incorrect list of authors which is now corrected.

A mechanism of stimulation of low-temperature plasma anodization using a catalyst or ultraviolet radiation in the case of the formation of oxide films of metals and semiconductors is suggested. The stimulating effect of a catalyst or ultraviolet radiation on the process of plasma anodization is attributed to the appearance of an additional concentration of antibonding quasiparticles (electrons and holes) that weaken the chemical bonds in the anodized material. The conditions for implementing the stimulated processes are reported.

A new method for insulating the active elements of GaAs-based integrated circuits (ICs) is proposed, which is based on the use of intrinsic gallium arsenide oxide formed by plasma anodizing assisted with UV irradiation. This insulation provides a significant decrease in the level of leak currents and the parasitic substrate feedback, ensures an increase in the thermal stability and breakdown field strength, and is adapted to planar IC technology.

In order to achieve quantum interference of free electrons inside a solid, we have modified the geometry of the solid so that de Broglie waves interfere destructively inside the solid. Quantum interference of de Broglie waves leads to a reduction in the density of possible quantum states of electrons inside the solid and increases the Fermi energy level. This effect was studied theoretically within the limit of the quantum theory of free electrons inside the metal. It has been shown that if a metal surface is modified with patterned indents, the Fermi energy level will increase and consequently the electron work function will decrease. This effect was studied experimentally in both Au and SiO2 thin films of special geometry and structure. Work function reductions of 0.5eV in Au films and 0.2eV in SiO2 films were observed. Comparative measurements of work function were made using the Kelvin probe method based on compensation of internal contact potential difference. Electron emission from the same thin films was studied by two independent research groups using photoelectron emission microscopy.

ACKNOWLEDGMENTS This work is financed and supported by Borealis Technical Limited, assignee of corresponding patents (U.S. patent Nos. 6,281,514; 6,495,843; 6,680,214; 6,531,703; and 6,117,344) and all provisional and pending patent applications. All intellectual properties have been licensed to Avto Metals plc, Cool Chips pic, or Power Chips plc.

Presented at the 18th International Vacuum Nanoelectronics Conference (IVNC 2005), 10–14 July 2005, St. Catherine’s College, Oxford University, Oxford, United Kingdom.

REFERENCES

Changes in metal properties caused by periodic indents in the metal surface were studied within the limit of quantum theory of free electrons.

Modification of properties of metal films caused by indents on their surface are studied. It is shown that indents on a film surface lead to quantum state depression (QSD), i.e., a decrease in the density of quantum states of a free electron. The density of the wave vector in the k-space decreases throughout the Fermi sphere. At the same time, the total number of electrons is conserved, since the metal remains electrically neutral. According to the Pauli Exclusion Principle, some electrons will occupy states with higher wave numbers. The Fermi vector and the Fermi energy of the thin metal films increase and, therefore, the work function decreases. Experiments have demonstrated a decrease in the work function of the thin indented films of Au, Nb, Cr, and SiO2. Experimental results are qualitatively consistent with the theoretical predictions.

We have obtained tunneling currents of over 10 /spl Aring/ through the vacuum gap between conformal electrodes having an effective area on the order of 0.1-1 cm/sup 2/. The large area vacuum gap is obtained by using a surface replication method that allows for two electrodes to have precisely matched topographies. The width of the vacuum gap within the range of 30-100 /spl Aring/ is regulated using piezoelectric actuators. These same actuators are used to regulate angles between the electrodes. Measured I-V characteristics show that the overall current through the system can be represented as the sum of the tunneling current and the current running through the short circuits between electrodes, and that tunneling current becomes dominant at distances greater than 30 /spl Aring/. The dependence of the capacitance and conductance on the distance between electrodes is in good agreement with the simple model of electrodes separated by a vacuum gap. Such an electron tunneling device could be used for cooling and power generation, as well as for other applications.