At present there is no ‘ideal’ thin-film transistor technology for demanding display applications, such as organic light-emitting diode displays, that allows combining the low-temperature, solution-processability offered by organic semiconductors with the high level of performance achievable with microcrystalline silicon1. N-type amorphous mixed metal oxide semiconductors, such as ternary oxides Mx1My2Oz, where M1 and M2 are metals such as In, Ga, Sn, or Zn, have recently gained momentum because of their high carrier mobility and stability2, 3 and good optical transparency, but they are mostly deposited by sputtering. So far no route is available for forming high-performance mixed oxide materials from solution at low process temperatures <250 °C. Ionic mixed metal oxides should in principle be ideal candidates for solution-processable materials because the conduction band states derived from metal s-orbitals are relatively insensitive to the presence of structural disorder and high charge carrier mobilities are achievable in amorphous structures2. Here we report the formation of amorphous metal oxide semiconducting thin-films using a ‘sol–gel on chip’ hydrolysis approach from soluble metal alkoxide precursors, which affords unprecedented high field-effect mobilities of 10 cm2 V−1 s−1, reproducible and stable turn-on voltages Von≈0 V and high operational stability at maximum process temperatures as low as 230 °C.
Amorphous mixed metal oxides are
emerging as high performance semiconductors
for thin film transistor (TFT) applications, with indium gallium zinc
oxide, InGaZnO (IGZO), being one of the most widely studied and best
performing systems. Here, we investigate alkaline earth (barium or
strontium) doped InBa(Sr)ZnO as alternative, semiconducting channel
layers and compare their performance of the electrical stress stability
with IGZO. In films fabricated by solution-processing from metal alkoxide
precursors and annealed to 450 °C we achieve high field-effect
electron mobility up to 26 cm2 V–1 s–1. We show that it is possible to solution-process
these materials at low process temperature (225–200 °C
yielding mobilities up to 4.4 cm2 V–1 s–1) and demonstrate a facile “ink-on-demand”
process for these materials which utilizes the alcoholysis reaction
of alkyl metal precursors to negate the need for complex synthesis
and purification protocols. Electrical bias stress measurements which
can serve as a figure of merit for performance stability for a TFT
device reveal Sr- and Ba-doped semiconductors to exhibit enhanced
electrical stability and reduced threshold voltage shift compared
to IGZO irrespective of the process temperature and preparation method.
This enhancement in stability can be attributed to the higher Gibbs
energy of oxidation of barium and strontium compared to gallium.
We have evaluated the electrical degradation of the Zincoxide(ZnO) varistors added two kinds of additives by the V-I measurements and the improved ICTS method. Results of the V-I characteristics show that both the characteristics of varistors added Bi2O3 and CoO and those added Bi2O3 and MnO2 were recovered by thermal annealing. This indicates that the distribution of O2-ion changed by applying voltage was returned to the initial condition by thermal annealing. Results of the improved ICTS measurement show that the trap density for varistors added Bi2O3 and CoO decreased after degradation. Trap levels for varistors added Bi2O3 and MnO2 became shallower after degradation. The result of simulation shows that varistors with narrow distribution of trap levels, deep trap levels and the low donor density have excellent nonlinear characteristic.
The rutile TiO 2 interlayer is inserted between HfO 2 and Ge to passivate a Ge surface. XPS results show that the GeO x formation was effectively suppressed. capacitance-voltage characteristic shows EOT = 0.84 nm and small hysteresis. These results suggest the Ge surface passivation utilizing the rutile TiO 2 interlayer is promising for the future Ge MOS devices.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.