Synaptic transistors with aluminum oxide dielectrics enabling full audio frequency range signal processing

Abstract

The rapid evolution of the neuromorphic computing stimulates the search for novel brain-inspired electronic devices. Synaptic transistors are three-terminal devices that can mimic the chemical synapses while consuming low power, whereby an insulating dielectric layer physically separates output and input signals from each other. Appropriate choice of the dielectric is crucial in achieving a wide range of operation frequencies in these devices. Here we report synaptic transistors with printed aluminum oxide dielectrics, improving the operation frequency of solution-processed synaptic transistors by almost two orders of magnitude to 50 kHz. Fabricated devices, yielding synaptic response for all audio frequencies (20 Hz to 20 kHz), are employed in an acoustic response system to show the potential for future research in neuro-acoustic signal processing with printed oxide electronics.

Chemical and Structural Characterization of Amorphous and Crystalline Alumina Obtained by Alternative Sol–Gel Preparation Routes

“…Alumina, although it had its glory years as a new material a few decades ago, is still one of the most important technical ceramics [ 1 ]. It has all-round uses, for instance in the field of catalysis [ 2 , 3 , 4 ], as catalyst supports or converters, as a transparent ceramic for high pressure sodium lamps or for lasers [ 5 , 6 ], in refractories or in electronics [ 7 , 8 ] as substrates for microelectronic computer chips.…”

Photoinduced Synaptic Behavior of InxTiyO Thin Film Transistors

“…Instead, the PPF tend to decrease due to the increasing number of generated electrons which recombine with the trapped holes. The relative high PPF values obtained from our devices proves the longer‐term retention of the channel conductance 31 . Because, higher PPF values indicates large amount of remaining charges even after pulse removal and this require a long time to remove the increased current in synaptic behavior, indicating long life time.…”

Engineering Bilayer AlOx /YAlOx Dielectric Stacks for Hysteresis-Free Switching in Solution-Processed Metal-Oxide Thin-Film Transistors

“…(Futscher et al, 2020). Residuals in the AlO x dielectrics, such as H + and OH − ions, were reported partly responsible for the enhanced quasi-static frequency polarization in the dielectric (Daunis et al, 2018;Bolat et al, 2020;Liang et al, 2020b). Secondary ion mass spectroscopy (SIMS) measurements were performed on the bilayer dielectrics spin-coated on Si wafers to investigate the hypothesis in detail.…”

“…The flexible TFTs with DUV annealed YAlO x dielectrics (Bolat et al, 2019) included positive shifts in the V T due to positive gate bias stress, which is a sign of negative charge trapping within the dielectric. In contrast, the devices with DUV annealed AlO x dielectrics (Bolat et al, 2020) (Mancinelli et al, 2020) had counter clockwise hysteresis in their transfer characteristics as a sign of positive charge trapping in the dielectric layer. In this study tuning the sign and magnitude of the hysteresis in the transfer characteristics of the TFTs is implemented by stacking solution-processed AlO x and YAlO x layers cured with deep ultraviolet assisted annealing at 250 °C as the insulators of the devices.…”

“…This property, if happens in the dielectric layer, results in hysteretic switching behavior of the TFTs. Depending on the behavior of the defects (or residuals) clockwise (Bolat et al, 2019) or counterclockwise hysteresis (Bolat et al, 2020) can be observed in the transfer characteristics of the device. Counterclockwise hysteresis was reported with various dielectrics cured at low temperatures (T < 300 °C) such as AlO x (Liang et al, 2020a), GdO x (Zhou et al, 2020), and ZrO x (Kim et al, 2020).…”