Fabrication
A huge number of conventional techniques already used by the microelectronics
industry can be successfully applied for fabricating thermoelectric devices. Such
techniques include the photolithography, electroplating, wafer dicing, and pick-andplace
systems. This allows the fabrication of a wide spectrum of thermoelectric devices
that range from the simple modules for handling a few microwatts [58] (in cooling or
energy conversion) to more complex module arrays (to handle higher power
levels) [59].
The quality of the deposited thin-films (either both constitutive layers or the entire
superlattice) must be high in order to successfully fine-tuning the thin-film thicknesses
in a superlattice so as to hinder lattice vibrations (thus decreasing heat flow) and
transmit electrons (increasing electrical conductivity), using materials that intrinsically
have a large thermopower; this generates a thermoelectric material with a particularly
high figure-of-merit [60]. The conventional imaging techniques based on X-rays
diffractions don’t offer satisfactory resolution to make a quality assessment of the
surface of the deposited thin-films. In this context, the Scanning Probe
Microscopy (SPM) technique fills such a gap, because high-resolutions of a few
picometres can be obtained. This is due to the resolution to be only dependent of the
size of the probe-sample interaction volume [61].