Figure 2. Material characterization and basic DC electrical
measurements of the ion-modulated memtransistor. a) Schematic of the
ion-modulated memtransistor structure, the channel and solid-state
electrolyte are composed of niobium oxide (NbOx) and
lithium phosphorous oxynitride (LiPON), respectively, and silicon oxide
act as the passivation layer to keep the electrolyte from oxygen and
moisture. b) Optical microscope of ion-modulated memtransistor. c) the
cross-sectional TEM image of the central part within the device. d)
Elemental mapping of the materials in the device for O, P, N, Nb, Si,
Ti, and Au, respectively. e) The line scan EDS of the device
cross-section, which corresponds to the red arrow in d). f) Crystal
structure of lithium phosphate is composed mainly of
(PO4)3- tetrahedrons, and lithium ions
that are closely bonded to oxygen atoms. In the right part,the P-N and
P=N bonds are formed when the nitrogen atoms are doped in
Li(PO4)3 crystal. g) Transfer curves of
the ion-modulated memtransistor with gate bias swept from -6 V to 4 V at
the sweeping rate of 0.53 V/s, which exhibiting counterclockwise
hysteresis and the average on/off ratio at 0 V gate bias is
approximately 125, the corresponding drain current Id is
monitored by applying small 0.1 V DC bias at the drain terminal. The
grey lines represent the results of thirty continuous DC sweeps, and the
red line represents the average value of these curves. h) Statistical
data of drain current Id at the on-state or off-state
within thirty DC cycles. i) Leakage currents(Ig)
variation corresponding to the DC sweeps in g) show the maximum is below
800 pA, which can help reduce energy cost when programming the device.
Transfer curves at different sweeping dynamic ranges. j) and sweeping
rate k), the drain-source bias is still kept at 0.1 V.