United States

The metallic to semiconducting resistivity ratios and the transition temperature sharpness of annealed atomic layer deposited (ALD) VO2 films on amorphous silicon dioxide are found to depend on grain size in a closely similar way to films from previous sputtered or pulse laser deposited work. This occurs because the dominance of grain growth and compaction processes leads to a common scaling of properties with grain size. Density functional simulations find that V-V dimerizations allow grain boundaries to remain semiconducting but with reduced band gap, while others create metallic grain boundaries, reducing the resistivity ratio for smaller grains in both cases.

Materials Challenges for Memory

Microstructure Scaling of Metal-Insulator Transition properties of Atomic Layer Deposited VO2 films

metal-insulator transition

[![](https://assets.underline.io/uploads/markdown_image/1/image/985c8a40b04e56675221c8549975de3c.png)](https://drive.google.com/file/d/1B70nPIeeeqdG4UU70NlYXuKVOHLRuJEo/view?usp=sharing)

### ** History of DRC**
The Device Research Conference (DRC) began in the pre-transistor era with the 1942 establishment of the Conference on Electron Device Research (CEDR). Following William Shockley’s 1948 CEDR presentation of the transistor device, the Solid-State Device Research Conference (SSDRC) was established, with invitation-only attendance.

In the ensuing decades, many exciting firsts were presented at SSDRC, including the use of impurity diffusion in silicon and germanium, the first practical MOSFET, and the first lattice-matched heterojunction.

In 1969, under the leadership or Herbert Kroemer and Cal Quate, the CEDR and SSDRC merged into DRC. In 1970, attendance was opened to all, and the first DRAM (dynamic random-access memory), room temperature lasers, and first CCD (charge-coupled device) were reported—all in the same 1970 DRC meeting!

1976 saw the first official coordination of tandem meetings between DRC and the Electronic Materials Conference (EMC) to bring together the electronic materials and device communities—a custom which persists to this day. In 1991, DRC began publishing its digest with IEEE; they can all be found [here on IEEE Xplore](https://ieeexplore.ieee.org/xpl/conhome/1000199/all-proceedings). Throughout this period, DRC featured reports of many novel and record-setting devices, including the HEMT (High Electron Mobility Transistor), VCSEL (Vertical Cavity Surface Emitting Laser), HBT (Heterojunction Bipolar Transistor), and nanoscale MOSFETs.

In recent years, DRC has continued to be the world’s premier forum to present innovative semiconductor device research with work on organic thin film transistors, graphene and carbon nanotube transistors, and 2D materials all featuring prominently in the 1990s through to the present day. In 2017, we celebrated DRC’s 75th anniversary with special sessions and an [article in the Journal of the Electron Device Society](https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=8168249&isnumber=8232486). DRC technical topics continue to evolve with emerging device trends such as memory devices, quantum devices, optoelectronics/photonics, and wide bandgap power devices to reflect the exciting work being done by a diverse community of device engineers around the globe.

Today, as we look forward to the next 75+ years of device innovation, DRC continues to lead the way in showcasing top-caliber research, facilitating vibrant discussion and debate and acting as a platform to nurture the next generation of device engineers. We welcome you to join us at the next DRC!

To learn more about DRC's history, please see [Aaron Franklin, Debdeep Jena and Deji Akinwande, "75 Years of the Device Research Conference—A History Worth Repeating," in IEEE Journal of the Electron Devices Society, vol. 6, pp. 116-120, 2018. doi: 10.1109/JEDS.2017.2780778](https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=8168249&isnumber=8232486).

### **Topics**
* Biological Devices
* Devices for Extreme Conditions
* Heterogeneously Integrated Devices
* Memory Devices
* Modeling and Simulation of Devices
* Nanoscale and Vacuum Devices
* Optoelectronic and Optical Devices
* Other Emerging Devices
* Power Devices
* Quantum Devices
* RF and Terahertz Devices
* Spintronic and Magnetic Devices
* Thin-film Devices
* Wide-bandgap Devices
 
### **Invited Speakers**
* Patrick Fay, University of Notre Dame
* Susanne Hoffmann-Eifert, Peter Grünberg Institute
* Sanghyeon Kim, Korea Advanced Institute of Science and Technology
* Sriram Krishnamoorthy, University of California, Santa Barbara
* Mario Lanza, King Abdullah University of Science and Technology
* Xiuling Li, The University of Texas at Austin
* Marko Radosavljevic, Intel Corporation
* Siddharth Rajan, The Ohio State University
* Giordano Scappucci, Delft University of Technology
* Fisher Yu, University of Arkansas
* Wenjuan Zhu, University of Illinois at Urbana-Champaign




Registration is required to attend this event. If you have not already done so, please use the link below to register for a ticket to the conference:

https://www.mrs.org/drc-2022/registration

Registration Is Required

DRC 2022

DRC continues to be the world’s premier forum to present innovative semiconductor device research with work on organic thin film transistors, graphene and carbon nanotube transistors, and 2D materials all featuring prominently in the 1990s through to the present day. In 2017, we celebrated DRC’s 75th anniversary with special sessions and an article in the Journal of the Electron Device Society. 
DRC technical topics continue to evolve with emerging device trends such as memory devices, quantum devices, optoelectronics/photonics, and wide bandgap power devices to reflect the exciting work being done by a diverse community of device engineers around the globe.

poster


![](https://assets.underline.io/uploads/markdown_image/1/image/2e10c515564e9ec3287ee4c664011c20.png)

The energy cost of storing and moving data is enormous, and is growing at such a rapid pace that within a few years the power demand may overwhelm some developed nations. Non-volatile memory (NVM) and neuromorphic computing are enabling critical advances in this area, but there are many scientific and technological challenges. This conference will cover the materials challenges of different memory technologies, from the fundamental processes and mechanisms, to industry perspectives on materials specifications and manufacturing.

Single-Molecule Magnets (SMM) and Single Ion Magnets (SIM) it are perspective materials for dense data storage. One molecule can contain 1 bit of information. Control over splitting of spin levels in SMM and SIM are usually controlled by external magnetic field tuned to satisfy conditions of effective thermally activated overcoming crystalline field barrier for magnetization reversal. We propose composite material containing known in advance SIM powder with magnetically hard microparticles (MPs) as an effective media changing to external magnetic field by magnetically controllable residual demagnetizing field of MPs.
In the SIM+MPs composite, we have found peaks of magnetic AC susceptibility on its frequency dependences in the absence of external magnetic field, while no peaks have been found for SIM and MPs powders measured separately in similar conditions. We have found the dependence of AC susceptibility of SIM on remnant magnetization of the MPs. Significance of the obtained results is the development of a very simple experimental method eliminating necessity of permanent magnet and external field to
reveal spin transitions in SIM. Ferromagnetic inclusions incorporated in SIM powder create high enough local residual demagnetizing field able to control over splitting of spin levels in small groups of SIM complexes. 
The work was supported by the Russian Foundation for Basic Research grant № 20-33-90256.

Magnetic memory of composite based on single ion magnet biased by dipolar field of microparticles

We obtain orthorhombic HfO2 ferroelectric phase induced by Ge component in 3-layers of control HfO2/floating gate of Ge NPs in HfO2/tunnel HfO2/p-Si.
3-layer structures are deposited by magnetron sputtering (MS) of HfO2/Ge-HfO2/HfO2 layers stack on Si wafer and nanostructured by RTA.1–3 As-deposited Ge-HfO2 intermediate (int.) layer is rich in Ge (≈60% Ge). Morphology, structure, composition is investigated by HRTEM, HAADF-STEM, EDX, SAED, GI-XRD. Polarization studies are carried out by P–V hysteresis loops measurements, PFM and DFT. Memory properties are evidenced by C–V hysteresis loops.
We demonstrate the HfO2 orthorhombic phase formation in floating gate with extension in adjacent layers (control – ctr. & tunnel – tun. HfO2). Total Pr reaches ~7 µC/cm2 - very high for the 3-layer structures having minimum thickness of 35 nm.
These memory structures have very high memory window (ΔV) of C–V hysteresis due to both contributions of Ge NPs as charge storage nodes & ferroelectric HfO2.
1. Nanotechnology 30, 365604 (2019) 2. Nanotechnology 28, 175707 (2017)
3. Nanotechnology 31, 495207 (2020) 4. Appl. Phys. Lett. 113, 213106 (2018)

Ferroelectric orthorhombic HfO2 phase in 3-layer memory structures of control HfO2 /floating gate of Ge nanoparticles in HfO2 /tunnel HfO2 on Si wafers

Resistive random access memory (RRAM) is a promising candidate for the memory, logic and neuromorphic device exhibiting advantage in power consumption. Tantalum oxide is an attractive candidate, as the material exhibits rich and complex electrically resistive switching behaviors. It varies based on the film composition, the structure (e.g., crystallinity), and the mode of electrical operation. 
In this study, we focused on the resistive switching behavior of tantalum oxide through the atomic layer deposition (ALD) using tantalum ethoxide and water depending on the ALD deposition cycle. The stable resistive switching properties was obtained with TaOx film in 250 ALD cycle. Film thickness was measured by using surface profiler. X-ray photoelectron spectroscopic analysis was carried out to analyze the chemical state of the films. The electrical performance was obtained via current-voltage measurement at room temperature. Through these analyses, we aimed to demonstrate the relation between the film thickness and the resistive switching behavior of tantalum oxide thin films. 


A study on the nonvolatile memory characteristics of tantalum oxide thin films formed by atomic layer deposition

Tin oxide (SnO2) has received significant attention in both industries and academia due to its attractive features such as wide bandgap (3.6 eV), n-type semiconductivity, and surface chemistry, and useful for several applications such as transparent electronics, electrochemical storage devices, sensors and catalysis. It is also attractive for memristor or resistive random access memory (RRAM) devices due to its tunable defect density. Although some reports are present on it, reports that show analog switching characteristics and cyclic stability are very scarce in the literature. Here, in this work, we demonstrate Pt/SnO2/Pt RRAM devices that show more than 10 resistive states (or analog switching characteristics), good cyclic stability (>100 cycles) and retention measurements (>1000 seconds). Moreover, these devices do not require any compliance current (compliance-free) during set and reset, and require very low voltages to operate (≤2 V). Furthermore, these devices show pulse width dependence characteristics, which gives the flexibility of programming and erasing with different voltage pulses. Therefore, these low power, compliance-free SnO2 RRAM devices with analog switching characteristics can pave the way for new window of applications such as portable gasistors and neuromorphic computing devices.

Compliance-free, analog switching characteristics of SnO2 based memristors

The rapid development of memory devices has brought the areal density to approach 10 Tb/in2 (i.e., nearly 244 bits or 44 independent memory units in the area of one square inch), corresponding to an average size around 10 mm2 (or 33 mm2) for one memory unit. Thanks to the interfacial lattice coupling and switchable electric polarization, the artificially-designed perovskite oxide multilayers are capable to exhibit magnetically-working units with the characteristic length of only a few nanometers. For examples, the 12-unit-cells nonmagnetic SrTiO3 (or PbTiO3) spacers can make the 9-unit-cells ferromagnetic (La,Sr)MnO3 layers switch independently in a multilayer heterostructure, of which the functional unit is only 21 unit cells or around 8 nm. Also, the paramagentic CaRuO3 spacer can continuously change the bond angle in the adjacent ferromagnetic (La,Ca)MnO3 layer, resulting in multiple tunable coercivities in a coherently-grown multilayer. More importantly, our recent data show that the thickness of those spacers can be further reduced to 3~4 unit cells (1.2-1.6 nm), while the independence of each magnetic layer is still maintained. Our results demonstrate the promising potentials of well-designed heterostructures in high-density memory devices.

Towards High Density Memory Devices Using Perovskite Oxide Heterointerfaces

The ever-increasing demand for data storage has driven the development of many cryogenic memory storage technologies. Among these, magnetic random-access memory (MRAM) in the form of magnetic tunnel junctions (MTJs) has emerged as a leading candidate. MTJs have proven successful as a means of data storage, but the large resistance of the tunnel barrier prevents this structure from integration with other low-temperature technologies such as superconducting computing.

Use of a low-resistance barrier, such as in a GMR device using current perpendicular to plane geometry (CPP), has potential to solve this issue, however now we are presented with the opposite problem of having too low resistance. Here we present a way to model this problem and thereby provide a solution to find a ‘Goldilocks’ zone for the conductivity ratio of each layer that allows for a reliable and meaningful voltage readout.

Furthermore, we propose a series of materials with a tunable conductivity that is dependent on the initial growth parameters to replace the commonly used transition metals in this endeavor. The rare-Earth nitride (REN) series are ferromagnetic semiconductors with massive tunability and show promise for integration with existing superconducting technologies.

Cryogenic memory storage using tunable ferromagnetic semiconductors

The field of magnetic random-access memory (MRAM) has captivated immense recognition recently given its capability to provide non-volatility along with accelerated read and write performance. Conventional MRAM devices based on spin-orbit torque (SOT)1, spin-transfer torque (STT)2, or current-driven methods employ magnetization switching using external current. The current-based methods accompany thermal issues and thereby surges the power dissipation. An attractive alternative that has emanated lately is a conception of straintronic (STR) based MRAM devices to store information. To carry out magnetization switching in STR devices external small voltage is employed. Currently, in STR-based MRAM devices, the magnetization reversal without external bias magnetic field is not explored. Although external bias is not desired since it increases device size and cost and lessens thermal stability and retention time by lowering the energy barrier between two extremes stable states.
In this work, size-dependent in-plane magnetization switching of elliptical multiferroic magnets of FeGaB on single-crystal PMN-PT (011) piezoelectric are studied using the finite element method (FEM). To ensure minimum thickness (dmin) for multiferroic magnets in-plane induced energy well (∆E) is scaled by kbT, such that if ∆E/ kbT ≤ 70, STR based MRAM device is thermally unstable. To investigate maximum thickness corresponding to self-biasing (dsb), pre-stress equilibrium exchange and demagnetization energy of multiferroic magnets are examined against thickness. Large size magnets strive to diminish the energy by line up magnetization with magnet boundary that ultimately causes vortex state. Oppositely smaller size magnets strive to diminish the energy by line up magnetization along the easy axis (0o or 180o) of the multiferroic magnet. This examination is deciding after all such self-biasing would give superiority to future STR-based MRAM devices because it gets rid of an external magnetic bias field. Even though the thickness range of dmin≤d≤dsb gives an idea about the STR-MRAM device that is stable and self-bias without applying the external magnetic bias field, it is observed that maximum thickness (dmax) for in-plane 180o magnetization switching is limited by critical stress requirement. When external stress more than or equivalent to critical stress is generated using external voltage, in-plane 90o magnetization switching is observed (Fig 1(a)) from the pre-stress state (0o or 180o). The critical stress requirement for fixed thickness and increased cross-sectional area rises. During in-plane 90o magnetization switching exchange and stress anisotropy energies are observed almost negligible and the demagnetization energy rises since the magnetization is switched from the easy axis to the hard axis. To obtain in-plane 180o switching magnetic precession is used. As soon as the magnetization component along the x-axis reaches its maximum negative value, removal of external voltage causes another 90o switching (Fig 1(b)) since the multiferroic magnet makes an effort to reduce its total energy by falling to its nearest easy axis. In-plane fastest 180o magnetization switching time and associated external strain are probed. For fixed cross-sectional area, when the thickness is increased trade-off between the fastest switching time and associated switching energy is observed. For fixed thickness, when the cross-sectional area is increased faster switching time and lesser switching energy is observed. This work validates and verifies the STR-based MRAM device that abolishes the external magnetic bias field and achieves in-plane 180o magnetization switching.
Reference 
1C. Zhang, S. Fukami, H. Sato, F. Matsukura and H. Ohno, Appl. Phys. Lett. 107, 012401 (2015).
2C.F. Pai, L. Liu, Y. Li, H. W. Tseng, D. C. Ralph and R. A. Buhrman, Appl. Phys. Lett. 101, 122404 (2012).


Strain-induced magnetization switching in FeGaB nanomagnets for self-biased MRAM applications

Change of angular dependence of magnetoresistance derivative in CoFeB/Ta/CoFeB platform under nanoparticles Fe/Fe3O4, deposited on sample surface was observed. 
In Р+ state of the CoFeB/Ta/CoFeB platform effective anisotropy of the system “platform-particle” is strongly reduced to the value close to zero. This happens due to compensation of positive anisotropy of the areas not covered by nanoparticles by strong negative anisotropy of those areas covered by nanoparticles.
Comparison between the Atomic Force and Magnetic Force Microscope images and subtraction of corresponding phase contrasts allows visualization of the film magnetization affected by the particles.
Theoretical estimation and OOMMF modeling of the diameter of the CoFeB film area, which magnetization is reversed under the dipolar magnetic field created by the Fe/Fe3O4 particle, are obtained. They are found to be in good agreements with the area observed experimentally. 


Microwave magnetoresistance of CoFeB spin valves covered with nanoparticles

An abrupt reduction in resistance called forming is required for resistance switching phenomenon in ReRAM structures using a binary oxide such as nickel oxide (NiO). In this study, dependence of the forming characteristics on applied voltage, cell size, and ambient temperature were investigated under constant voltage stresses to Pt/NiO/Pt stack structures. Many experimental results suggest that the formation of conductive filaments at forming follows a weakest link theory, and that weakest spots are randomly distributed in the NiO film according to the Poisson statistics. Moreover, at a high temperature of 400K, gradual reduction phenomena in resistance were observed before the forming process, which indicates that defects in the ultrathin layer in the NiO can occur continuously due to electrical stress as the ambient temperature elevate.

Thermal effect of Forming Characteristics in NiO-based ReRAM cells

Emerging memory technologies show the potentials of new memory devices to store more data at a lower cost compared to the industry-standard silicon-based devices. Among these, resistive switching random access memory (RRAM) devices, which are based on the metal-insulator-metal (MIM) structure, have shown potential in non-volatile memory applications due to their characteristics of low-power consumption, superior switching speed, excellent reliability, ultimate scaling potential with the simple fabrication process and adaptive aptitudes for the neuromorphic applications [1, 2]. 
The advantage of the biodegradable materials is non-toxic and eco-friendly but the essential material properties remain the major issues in the scaling of biomass-based RRAMs [3]. Biodegradable magnesium fluoride (MgFx) is an insulator with a large bandgap (11.3 eV) which makes it a favorable candidate for biodegradable RRAM devices. Recently, a couple of reports on MgFx based RRAM devices have shown excellent resistive switching and biodegradable properties [2, 4]. Nevertheless, the conduction mechanism and resistive switching mechanism in the MgFx based RRAM devices are not fully understood. The electrodes in RRAM devices may significantly affect the resistive switching (RS) behavior. The effects of electrode materials and operating environment including cryogenic temperature on the device performance have not been studied yet. 
In this study, we report resistive memory devices employing MgFx as the resistive switching layer that is inserted between the platinum and titanium metal electrodes. The MgFx based RRAM devices exhibit electroforming free bipolar resistive switching characteristics at room temperature and open-air environment. We also report the effects of electrode materials (Top: Pt, Au/Ni, ITO, and Bottom: p+ Si, n+ Si, ITO) on MgFx based RRAM devices. It is found that the difference in workfunctions affects the performances of the devices. We have also analyzed the effect of the operating environment as well as temperature from room temperature down to cryogenic temperature. The detailed performance of the devices, their conduction and switching mechanisms, the effects of the electrode materials, and the operating environment including cryogenic temperature will be presented at the virtual conference.


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Microstructure Scaling of Metal-Insulator Transition properties of Atomic Layer Deposited VO2 films

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Magnetic memory of composite based on single ion magnet biased by dipolar field of microparticles

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