Engineering topics

Lin, Jianqiang

Publications and source records attributed to Lin, Jianqiang.

4 records

DOE OSTI2018

Vanadium Dioxide Circuits Emulate Neurological Disorders

Information in the central nervous system (CNS) is conducted via electrical signals known as action potentials and is encoded in time. Several neurological disorders including depression, Attention Deficit Hyperactivity Disorder (ADHD), originate in faulty brain signaling frequencies. Here, we present a Hodgkin-Huxley model analog for a strongly correlated VO 2 artificial neuron system that undergoes an electrically-driven insulator-metal transition. We demonstrate that tuning of the insulating phase resistance in VO 2 threshold switch circuits can enable direct mimicry of neuronal origins of disorders in the CNS. The results introduce use of circuits based on quantum materials as complementary to model animal studies for neuroscience, especially when precise measurements of local electrical properties or competing parallel paths for conduction in complex neural circuits can be a challenge to identify onset of breakdown or diagnose early symptoms of disease.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2018

Electrically Driven Insulator–Metal Transition-Based Devices—Part I: The Electrothermal Model and Experimental Analysis for the DC Characteristics

We present a device model for the electrically driven insulator-to-metal transition (E-IMT) that captures the essential physics in E-IMT and can be used for physical device simulations and mixed-mode simulations of circuits containing IMT elements. Aspects of the model include the temperature-dependent resistivity, Joule heating, heat transport, and the spatial and dynamic coupling of the above phenomenon. We show that the model captures the dc and transient characteristics as measured by experiments. The model points out the existence of two critical transition voltages (V c ) under bidirectional sweep, the physical origin of this hysteresis, and correctly predicts the scaling of the critical voltage for transition V c with the device size. The models' effectiveness as a basis for developing a mixed-mode circuit simulator is shown via comparison with experimental data for a steep-swing hybrid-field-effect transistor.

Lin, Jianqiang↗

DOE OSTI2018

Electrically Driven Insulator–Metal Transition-Based Devices—Part II: Transient Characteristics

Part II of this paper discusses the transient characteristics of the electrically driven insulator–metal transition (E-IMT) material-based device. To model the full transient characteristics, we modify the electrothermal model developed in Part I to capture extrinsic capacitance and 2-D heat transport effects. In order to test the model against the experiment, we fabricated and tested scaled E-IMT devices with a necked-down design to minimize nonhomogeneity. We show excellent agreement of the predictions of the model with the experimental data, and we find that the IMT device goes through three stages before a steady state is established.These three stages are identified as the times required for the incubation of the IMT transition, positive feedback, and width expansion of the IMT zone within the device. The impact of capacitance and 2-D heat transport is discussed. Furthermore, we show an inverse relation arises between the incubation time and the applied voltage. This paper satisfactorily explains the turn-on transient in a nanoscale E-IMT device within the framework of our electrothermal (Joule heating) model.

Insulator–to-metal transition (IMT)↗

DOE OSTI2018

Silicon compatible Sn-based resistive switching memory

Large banks of cheap, fast, non-volatile, energy efficient, scalable solid-state memories are an increasingly essential component for today's data intensive computing. Conductive-bridge random access memory (CBRAM) – which involves voltage driven formation and dissolution of Cu or Ag filaments in a Cu (or Ag) anode/dielectric (HfO 2 or Al 2 O 3 )/inert cathode device – possesses the necessary attributes to fit the requirements. Cu and Ag are, however, fast diffusers and known contaminants in silicon microelectronics. In this paper, employing a criterion for electrode metal selection applicable to cationic filamentary devices and using first principles calculations for estimating diffusion barriers in HfO 2 , we identify tin (Sn) as a rational, silicon CMOS compatible replacement for Cu and Ag anodes in CBRAM devices. We then experimentally fabricate Sn based CBRAM devices and demonstrate very fast, steep-slope memory switching as well as threshold switching, comparable to Cu or Ag based devices. Furthermore, time evolution of the cationic filament formation along with the switching mechanism is discussed based on time domain measurements (I vs. t) carried out under constant voltage stress. Finally, the time to threshold is shown to be a function of both the voltage stress (V stress ) as well as the initial leakage current (I 0 ) through the device.

42 ENGINEERING↗