Detection of charge storage on molecular thin films of tris(8-hydroxyquinoline) aluminum (Alq3) by Kelvin force microscopy: a candidate system for high storage capacity memory cells

Publication Type:

Journal Article


Nano Lett., ACS Publications, Volume 12, Issue 3, p.1260-1264 (2012)




2012, 2013 and earlier


Retention and diffusion of charge in tris(8-hydroxyquinoline) aluminum (Alq(3)) molecular thin films are investigated by injecting electrons and
holes via a biased conductive atomic force microscopy tip into the Alq(3)
films. After the charge injection, Kelvin force microscopy measurements
reveal minimal changes with time in the spatial extent of the trapped
charge domains within Alq(3) films, even for high hole and electron
densities of >10(12) cm(-2). We show that this finding is consistent with
the very low mobility of charge carriers in Alq(3) thin films (<10(-7)
cm(2)/(Vs)) and that it can benefit from the use of Alq(3) films as
nanosegmented floating gates in flash memory cells. Memory capacitors
using Alq(3) molecules as the floating gate are fabricated and measured,
showing durability over more than 10(4) program/erase cycles and the
hysteresis window of up to 7.8 V, corresponding to stored charge densities
as high as 5.4 × 10(13) cm(-2). These results demonstrate the potential
for use of molecular films in high storage capacity nonvolatile memory


PMID: 22332966