An energy-filtered cold electron device comprising: a central island disposed on an isolation layer, the central island having at least a first sidewall and a second sidewall, wherein the first and second sidewalls of the central island are opposite one another; a second tunneling barrier disposed on the first sidewall of the central island; an additional second tunneling barrier disposed on the second sidewall of the central island; a first tunneling barrier disposed on the second tunneling barrier and a first portion of the isolation layer; an additional first tunneling barrier disposed on the additional second tunneling barrier and a second portion of the isolation layer; a first electrode (source) disposed on the first tunneling barrier above the first portion of the isolation layer and adjacent to the first tunneling barrier disposed on the second tunneling barrier; a second electrode (drain) disposed on the additional first tunneling barrier above the second portion of the isolation layer and adjacent to the additional first tunneling barrier disposed on the additional second tunneling barrier; a gate dielectric disposed above the central island; and a gate electrode disposed on the gate dielectric; wherein the device is in a planar configuration; wherein the device comprises a sequential arrangement of the first electrode, the first tunneling barrier, the second tunneling barrier, the central island, the additional second tunneling barrier, first tunneling barrier; and the second electrode; wherein an electron energy filter is formed from (a) the sequential arrangement of the first electrode, the first tunneling barrier, and the second tunneling barrier, and (b) the sequential arrangement of the additional second tunneling barrier, the additional first tunneling barrier, and the second electrode; wherein the electron energy filter comprises a quantum well, formed in the first tunneling barrier, having discrete energy levels; wherein the device enables electron energy filtering through the discrete levels of the quantum well; and wherein the device has an effective electron temperature of less than or equal to 45 K without any external cooling, when electron reservoirs connected to the first and second electrodes are at room temperature. a central island disposed on an isolation layer, the central island having at least a first sidewall and a second sidewall, wherein the first and second sidewalls of the central island are opposite one another; a second tunneling barrier disposed on the first sidewall of the central island; an additional second tunneling barrier disposed on the second sidewall of the central island; a first tunneling barrier disposed on the second tunneling barrier and a first portion of the isolation layer; an additional first tunneling barrier disposed on the additional second tunneling barrier and a second portion of the isolation layer; a first electrode (source) disposed on the first tunneling barrier above the first portion of the isolation layer and adjacent to the first tunneling barrier disposed on the second tunneling barrier; a second electrode (drain) disposed on the additional first tunneling barrier above the second portion of the isolation layer and adjacent to the additional first tunneling barrier disposed on the additional second tunneling barrier; a gate dielectric disposed above the central island; and a gate electrode disposed on the gate dielectric; wherein the device is in a planar configuration; wherein the device comprises a sequential arrangement of the first electrode, the first tunneling barrier, the second tunneling barrier, the central island, the additional second tunneling barrier, first tunneling barrier; and the second electrode; wherein an electron energy filter is formed from (a) the sequential arrangement of the first electrode, the first tunneling barrier, and the second tunneling barrier, and (b) the sequential arrangement of the additional second tunneling barrier, the additional first tunneling barrier, and the second electrode; wherein the electron energy filter comprises a quantum well, formed in the first tunneling barrier, having discrete energy levels; wherein the device enables electron energy filtering through the discrete levels of the quantum well; and wherein the device has an effective electron temperature of less than or equal to 45 K without any external cooling, when electron reservoirs connected to the first and second electrodes are at room temperature.