Abstract

Three-dimensional (3D) stackable memory devices including nano-scaled crossbar array are central for the realization of high-density non-volatile memory electronics. However, an essential sneak path issue affecting device performance in crossbar array remains a bottleneck and a grand challenge. Therefore, a suitable bidirectional selector as a two-way switch is required to facilitate a major breakthrough in the 3D crossbar array memory devices. Here, we show the excellent selectivity of all oxide p-/n-type semiconductor-based p-n-p open-based bipolar junction transistors as selectors in crossbar memory array. We report that bidirectional nonlinear characteristics of oxide p-n-p junctions can be highly enhanced by manipulating p-/n-type oxide semiconductor characteristics. We also propose an associated Zener tunneling mechanism that explains the unique features of our p-n-p selector. Our experimental findings are further extended to confirm the profound functionality of oxide p-n-p selectors integrated with several bipolar resistive switching memory elements working as storage nodes.

Highlights

  • Representative I-V characteristic of the 1S and 1R elements demonstrating the outstanding nonlinearity of over 104 between Vread and Vread/2 (Vread is at 1.6 V) and large memory window of over 102. (c) Typical I-V characteristics of a serially connected selector and memory after completion of electrical connection, where a half voltage method was used. (d) High-resolution EDS (HR-EDS) elemental line profile across a line of the scanning transmission electron microscopy (STEM) image, where inset indicates a dark-field STEM image of the Pt/CoOx/IGZO/CoOx/Pt frame

  • This work focuses on all oxide semiconductor-based p-n-p junctions as a generic approach for highly distinct bidirectional switches, possibly enabling their use in 3D scalable crossbar arrays including in conventional complementary metal-oxide-semiconductor processes

  • P-/n-type oxide semiconductors are one of the most likely sources that can be used at low processing temperatures, and they allow easy control of lattice mismatch and dopant impurities in p-n hetero-junctions which are the strong plausibility that such a device based on oxide semiconductors might be easy for the formation of the 3D stacable structures with good uniformity performance due to significant controllability margin in thickenss and doping profiles during growth

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Summary

Results

As seen in this figure, the nonlinearity of the 1S selector is > 104 at a half-biased read scheme (Vread = 1.6 V and Vread/2 = 0.8 V). When an O2-reactive IGZO layer with an increased carrier concentration, band gap, and resistivity is involved in a 1S selector, the 1S selector shows a low off-current and a higher I-V slope after application of a turn-on voltage. We anticipate that this approach will become a simple and useful route that offers the possible realization of future 3D stackable crossbar array memory devices

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