MEMRISTORS AS RRAM

PRESENTED BY SAI KRISHNA.R (2-1)

NRIITTEJASWI.K(2-1)

NRIIT

Agenda

Memristor / RRAM

History

Applications

Physics

Conclusions Memristor, HP labs

THE PROBLEM

Flash memory currently commands the vast majority of the multibillion dollar non-volatile memory market, but experts agree that Flash memory feature sizes may not continue to scale well into the near future. As a result, most big players in the market are researching potential alternatives.

PROPOSED SOLUTION- RRAM

RRAM- RESISTIVE RAM

Resistive random-access memory (RRAM) is a new non-volatile memory type which promises to replace the existing flash memory

PRINCIPLE:

Resistive switching memories are based on materials whose resistivity can be electrically switched between high and low conductive states. RRAM has superior intrinsic scaling characteristics compared to the charge-based Flash devices, and potentially small cell size (enabling dense crossbar RRAM arrays using vertical diode selecting elements)

RRAM, one of the most recently proposed alternatives, takes advantage of controllable resistance changes in thin-oxide films. This could potentially provide greater density, lower power usage, greater speed, and lower cost than flash memory.

MEMRISTORS

ANALOGY

A common analogy for a resistor is a pipe that carries water. The water itself is analogous to electrical charge, the pressure at the input of the pipe is similar to voltage, and the rate of flow of the water through the pipe is like electrical current. Just as with an electrical resistor, the flow of water through the pipe is faster if the pipe is shorter and/or it has a larger diameter. An analogy for a memristor is an interesting kind of pipe that expands or shrinks when water flows through it.  If water flows through the pipe in one direction, the diameter of the pipe increases, thus enabling the water to flow faster. If water flows through the pipe in the opposite direction, the diameter of the pipe decreases, thus slowing down the flow of water. If the water pressure is turned off, the pipe will retain it most recent diameter until the water is turned back on. Thus, the pipe does not store water like a bucket (or a capacitor) – it remembers how much water flowed through it. .

MEMRISTORS?

memristors is a short for memory resistors which form, according to Lean Chua, one among the four basic elemnts , the other three being resistor, inductor, capacitor and resistor

Four interconnected things, mathematics says, can be related in six ways. Charge and current, and magnetic flux and voltage, are connected through their definitions. That's two. Three more associations correspond to the three traditional circuit elements. A resistor is any device that, when you pass current through it, creates a voltage. For a given voltage a capacitor will store a certain amount of charge. Pass a current through an inductor, and you create a magnetic flux. That makes five. Something missing?

History

2008: HP has a working memristor prototype

End of 1990s: Research on resistance switching

1971: The theory of the Memristor

1960s: Resistance switching

t

Memristor / RRAM

Memristor, HP labsMemristor symbol

Schematic view of RRAM cell

Al / TiOx / Al ”Sandwich”