Micro-cooler enhancements by barrier interface analysis

Abstract

A novel gallium arsenide (GaAs) based micro-cooler design, previously analysed both experimentally and by an analytical Heat Transfer (HT) model, has been simulated using a self-consistent Ensemble Monte Carlo (EMC) model for a more in depth analysis of the thermionic cooling in the device. The best fit to the experimental data was found and was used in conjunction with the HT model to estimate the cooler-contact resistance. The cooling results from EMC indicated that the cooling power of the device is highly dependent on the charge distribution across the leading interface. Alteration of this charge distribution via interface extensions on the nanometre scale has shown to produce significant changes in cooler performance.

Micro-coolers fabricated as a component in an integrated circuit

“…The equations describing the micro-cooler are given below: θ θθ For an ideal device where the micro-cooler is fabricated directly on an infinite ideal heat-sink, θ s will tend to 0 and equation (6)…”

“…The superlattice acted as a thermal block by reducing phonon transport thereby preventing heat flow back towards the cooled top cathode contact. The thermal conductivity of the superlattice was assumed to be 0.06 W cm −1 K −1 [5,6] and its electrical conductivity infinite. The Seebeck coefficient was assumed to be 270 μV K −1 [6], which corresponded to 50 nm layer of graded AlGaAs.…”

“…The thermal conductivity of the superlattice was assumed to be 0.06 W cm −1 K −1 [5,6] and its electrical conductivity infinite. The Seebeck coefficient was assumed to be 270 μV K −1 [6], which corresponded to 50 nm layer of graded AlGaAs. The top cathode contact of the micro-cooler was ohmic with an assumed contact resistance of 0.1 Ω [6].…”

“…The Seebeck coefficient was assumed to be 270 μV K −1 [6], which corresponded to 50 nm layer of graded AlGaAs. The top cathode contact of the micro-cooler was ohmic with an assumed contact resistance of 0.1 Ω [6].…”

“…The layers were grown by molecular beam epitaxy. The 50 nm graded region corresponded to a Seebeck coefficient, S, of approximately 270 μV K −1 [6]. Transmission line matrix test cells were also included on the wafer to enable measurement of the contact specific resistance (∼ × − 3 10 5 Ω cm 2 ) of the metallization layers making up the top (cathode) and bottom (anode) ohmic contacts of the micro-cooler.…”