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Sn-doped indium oxide (ITO) semiconductor nano-films are fabricated by plasma-enhanced atomic layer deposition using trimethylindium (TMIn), tetrakis(dimethylamino)tin (TDMASn), and O2 plasma as the sources of In, Sn and O, respectively. A shared temperature window of 150 °C– 200 °C is observed for the deposition of ITO nano-films. The introduction of Sn into indium oxide is found to increase the concentration of oxygen into the ITO films and inhibit crystallization. Furthermore, two oxidation states are observed for In and Sn, respectively. With the increment of interfaces of In–O/Sn–O in the ITO films, the relative percentage of In3+ ions increases and that of Sn4+ decreases, which is generated by interfacial competing reactions. By optimizing the channel component, the In0.77Sn0.23O1.11 thin-film transistors (TFTs) demonstrate high performance, including μ FE of 52.7 cm2 V−1 s−1, and a high I ON/ I OFF of ∼5 × 109. Moreover, the devices show excellent positive bias temperature stress stability at 3 MV cm−1 and 85 °C, i.e. a minimal V th shift of 0.017 V after 4 ks stress. This work highlights the successful application of ITO semiconductor nano-films by ALD for TFTs. [ABSTRACT FROM AUTHOR]

Ferroelectric field effect transistor (FeFET) memories with hafnium zirconium oxide (HZO) ferroelectric gate dielectric and ultrathin InO x channel exhibit promising applicability in monolithic three-dimensional (M3D) integrated chips. However, the inferior stability of the devices severely limits their applications. In this work, we studied the effect of single cycle of atomic-layer-deposited Al–O bonds repeatedly embedded into an ultrathin InO x channel (∼2.8 nm) on the Hf0.45Zr0.55O x FeFET memory performance. Compared to the pure InO x channel, three cycles of Al–O bonds modified InO x channel (IAO-3) generates a much larger memory window (i.e. drain current ratio between the programmed and erased devices) under the same program conditions (+5.5 V/500 ns), especially after post-annealing at 325 °C for 180 s in O2 (1238 versus 317). Meanwhile, the annealed IAO-3 FeFET memory also shows quite stable data retention up to 104 s, and much more robust program/erase stabilities till 105 cycles. This is because the modification of strong Al–O bonds stabilizes the oxygen vacancies and reduces the bulk trap density in the channel. Furthermore, it is indicated that the program and erase efficiencies increase gradually with reducing the channel length of the memory device. By demonstrating markedly improved performance of the HZO FeFET memory with the ultrathin IAO-3 channel, this work provides a promising device for M3D integratable logic and memory convergent systems. [ABSTRACT FROM AUTHOR]

The electronic-photonic convergent systems can overcome the data transmission bottleneck for microchips by enabling processor and memory chips with high-bandwidth optical input/output. However, current silicon-based electronic-photonic systems require various functional devices/components to convert high-bandwidth optical signals into electrical ones, thus making further integrations of sophisticated systems rather difficult. Here, we demonstrate thin-film transistor-based photoelectric memories employing CsPbBr3/CsPbI3 blend perovskite quantum dots (PQDs) as a floating gate, and multilevel memory cells are achieved under programming and erasing modes, respectively, by imputing high-bandwidth optical signals. For different bandwidth light input (i.e. 500–550, 575–650 and 675–750 nm) with the same intensity, three levels of programming window (i.e. 3.7, 1.9 and 0.8 V) and erasing window (i.e. −1.9, −0.6 and −0.1 V) are obtained under electrical pulses, respectively. This is because the blend PQDs have two different bandgaps, and different amounts of photo-generated carriers can be produced for different wavelength optical inputs. It is noticed that the 675–750 nm light inputs have no effects on both programming and erasing windows because of no photo-carriers generation. Four memory states are demonstrated, showing enough large gaps (1.12–5.61 V) between each other, good data retention and programming/erasing endurance. By inputting different optical signals, different memory states can be switched easily. Therefore, this work directly demonstrates high-bandwidth light inputting multilevel memory cells for novel electronic-photonic systems. [ABSTRACT FROM AUTHOR]

Recently, various two-dimensional materials have been reported to exhibit non-volatile resistance switching phenomenon. The atomristors, featuring memristor effect in atomically thin nanomaterials such as monolayer transition metal dichalcogenides and hexagonal boron nitride, have drawn much attention due to the extremely thin active layer thickness with the advantages of forming-free characteristic, large on/off resistance ratio and fast switching speed. To investigate the switching mechanisms in the 2D monolayers, we introduced an electrical characterization method by current sweeping to illustrate the detailed information hidden in the commonly used voltage-sweep curves. Multiple transition steps have been observed in the SET process of MoS2-based resistance switching devices. The different behaviors of transition steps were attributed to the number of defects or vacancies associated with the switching phenomenon, which is consistent with the previously reported conductive-bridge-like model for 2D atomristors. This work provides an approach using current sweeping to precisely characterize the resistance switching effect and inspires further research to optimize the defect distribution in 2D materials for the applications in multi-bit non-volatile memory and neuromorphic computing. [ABSTRACT FROM AUTHOR]

Ferroelectric field effect transistor (FeFET) memories with hafnium zirconium oxide (HZO) ferroelectric gate dielectric and ultrathin InO x channel exhibit promising applicability in monolithic three-dimensional (M3D) integrated chips. However, the inferior stability of the devices severely limits their applications. In this work, we studied the effect of single cycle of atomic-layer-deposited Al-O bonds repeatedly embedded into an ultrathin InO x channel (∼2.8 nm) on the Hf 0.45 Zr 0.55 O x FeFET memory performance. Compared to the pure InO x channel, three cycles of Al-O bonds modified InO x channel (IAO-3) generates a much larger memory window (i.e. drain current ratio between the programmed and erased devices) under the same program conditions (+5.5 V/500 ns), especially after post-annealing at 325 °C for 180 s in O 2 (1238 versus 317). Meanwhile, the annealed IAO-3 FeFET memory also shows quite stable data retention up to 10 4 s, and much more robust program/erase stabilities till 10 5 cycles. This is because the modification of strong Al-O bonds stabilizes the oxygen vacancies and reduces the bulk trap density in the channel. Furthermore, it is indicated that the program and erase efficiencies increase gradually with reducing the channel length of the memory device. By demonstrating markedly improved performance of the HZO FeFET memory with the ultrathin IAO-3 channel, this work provides a promising device for M3D integratable logic and memory convergent systems., (© 2023 IOP Publishing Ltd.)

The electronic-photonic convergent systems can overcome the data transmission bottleneck for microchips by enabling processor and memory chips with high-bandwidth optical input/output. However, current silicon-based electronic-photonic systems require various functional devices/components to convert high-bandwidth optical signals into electrical ones, thus making further integrations of sophisticated systems rather difficult. Here, we demonstrate thin-film transistor-based photoelectric memories employing CsPbBr 3 /CsPbI 3 blend perovskite quantum dots (PQDs) as a floating gate, and multilevel memory cells are achieved under programming and erasing modes, respectively, by imputing high-bandwidth optical signals. For different bandwidth light input (i.e. 500-550, 575-650 and 675-750 nm) with the same intensity, three levels of programming window (i.e. 3.7, 1.9 and 0.8 V) and erasing window (i.e. -1.9, -0.6 and -0.1 V) are obtained under electrical pulses, respectively. This is because the blend PQDs have two different bandgaps, and different amounts of photo-generated carriers can be produced for different wavelength optical inputs. It is noticed that the 675-750 nm light inputs have no effects on both programming and erasing windows because of no photo-carriers generation. Four memory states are demonstrated, showing enough large gaps (1.12-5.61 V) between each other, good data retention and programming/erasing endurance. By inputting different optical signals, different memory states can be switched easily. Therefore, this work directly demonstrates high-bandwidth light inputting multilevel memory cells for novel electronic-photonic systems.

Recently, various two-dimensional materials have been reported to exhibit non-volatile resistance switching phenomenon. The atomristors, featuring memristor effect in atomically thin nanomaterials such as monolayer transition metal dichalcogenides and hexagonal boron nitride, have drawn much attention due to the extremely thin active layer thickness with the advantages of forming-free characteristic, large on/off resistance ratio and fast switching speed. To investigate the switching mechanisms in the 2D monolayers, we introduced an electrical characterization method by current sweeping to illustrate the detailed information hidden in the commonly used voltage-sweep curves. Multiple transition steps have been observed in the SET process of MoS 2 -based resistance switching devices. The different behaviors of transition steps were attributed to the number of defects or vacancies associated with the switching phenomenon, which is consistent with the previously reported conductive-bridge-like model for 2D atomristors. This work provides an approach using current sweeping to precisely characterize the resistance switching effect and inspires further research to optimize the defect distribution in 2D materials for the applications in multi-bit non-volatile memory and neuromorphic computing.