  The operation of resistive and phase-change memory (RRAM and PCM) is
controlled by highly localized self-heating effects, yet detailed studies of
their temperature are rare due to challenges of nanoscale thermometry. Here we
show that the combination of Raman thermometry and scanning thermal microscopy
(SThM) can enable such measurements with high spatial resolution. We report
temperature-dependent Raman spectra of HfO$_2$, TiO$_2$ and Ge$_2$Sb$_2$Te$_5$
(GST) films, and demonstrate direct measurements of temperature profiles in
lateral PCM devices. Our measurements reveal that electrical and thermal
interfaces dominate the operation of such devices, uncovering a thermal
boundary resistance of 30 m$^2$K$^{-1}$GW$^{-1}$ at GST-SiO$_2$ interfaces and
an effective thermopower 350 $\mu$V/K at GST-Pt interfaces. We also discuss
possible pathways to apply Raman thermometry and SThM techniques to nanoscale
and vertical resistive memory devices.

Applied Physics;Mesoscale and Nanoscale Physics;Materials Science