high voltage organic non-volatilte thin film

7/30/2019 high voltage organic non-volatilte thin film

1/21

Jinimol P GeorgeECE A

Roll No.:53

LOW-VOLTAGE ORGANICNONVOLATILE THIN-FILM

TRANSISTOR MEMORY BASED ON A

P(MMA-GMA)

Al

O COMPLEX LAYER


2/21

OBJECTIVESOVERVIEW

INTRODUCTION

FABRICATION

ELECTRICAL CHARACTERISTICS

OUTPUT CHARACTERISTICS

TRANSFER CHARACTERISTICS

DYNAMIC STORAGE CYCLES


3/21

COMPARISON

ADVANTAGES APPLICATIONS

CONCLUSION


4/21

OVERVIEW

Fabrication

Study of electrical characteristics of OTFTmemory.

Comparison.


5/21

INTRODUCTION Non-volatile memory: Computer memory that

can retain the stored information even when

not powered. Thin-Film Transistor (TFT) : Field-effect

transistor made by depositing thin films of asemiconductor active layer as well as the

dielectric layer and metallic contacts over asupporting substrate.

Organic TFT: TFTs have also been made usingorganic materials.


6/21

Two methods to fabricate OTFT memory device.

1. Use ferroelectric materials or electret as the gate

dielectric layer. The direction of the polarization ofthe gate dielectric layer modulates the channel

conductance.


7/21

2. Use the floating-gate OTFT memory with the charge

storage in the floating-gate modulating the channel

conductance. Insert a complex layer between the semiconductor

and the dielectric.

Complex layer is: poly(methyl methacrylate co

glycidyl methacrylate)-Al-O [P(MMAGMA)-Al-O].


8/21

FABRICATION Gate electrode: Al film(30nm) is formed on a

cleaned glass substrates thermal evaporation.

The insulator polymer P(MMA-GMA) was coatedon the Al gate electrode from a solution in butyl

acetate and cross-linked for 30 min at 120 C.

Then a thin Al layer was formed by vacuum

thermal deposition on the surface of the P(MMA-GMA) film.


9/21

The heat treating at 120 C in the oven with

clean atmosphere.

A 30-nm-thick pentacene active layer was grownby thermal evaporation.

MoO3 (10 nm) and Al (100 nm) were thermally

deposited onto the active layer to form the

source

drain electrodes.


10/21


11/21

ELECTRICALCHARACTERISTICS


12/21

OUTPUT CHARACTERISTICS

Holes accumulated under applied negative VGS.

Ids(A)


13/21

TRANSFER CHARACTERISTICS

Transfer characteristics of the present OTFT memory in

linear region, by the (a) semiexponential scale and (b)linear scale.


14/21

Linear region , Vds= -1v.

Vgs sweeping from off to on and returning to off atthe different sweeping rates.

Cyclic Vgs - Hysteresis loop - anticlockwise

direction.Direction of Ep change with Eg - Hysteresis loop

Nonvolatile memory.

Slower the Vgs sweeps, the larger hysteresis

loop.

Vgs sweep


15/21

DYNAMIC STORAGE CYCLEVGS = 15, 0, and 15 V forP, R, and E, respectively.

The P/R/E dynamic cyclecurrents can remain repeatable

without degradation after 100

cycles.

After being programmed, the R IDS,1-state cankeep higher than 1 A. After being erased, the R

IDS,0-state was quickly increased at the initial

seconds and then maintained at a 10^-9 A

magnitude.


16/21

COMPARISON

Parameters Floating gateOTFT

OTFT memorybased P(MMA-GMA)

Channel

conductance

The charges

storage in thefloating-gate.

Polarization of

gate dielectriclayer.

Operatingvoltage

-50v to +50v -15v to +15v

Channel width 2000 m 2000 m


17/21

Channel length 30m 30 m

P/R/E voltage -50/0/+50v -15/0/+15

Linear region Vds = -5v Vds = -1v

Memory ratio 32 2010


18/21

ADVANTAGES Low operating voltage (-15 v to +15v)

Large memory ratio (2010)

Large memory window (13.3v) Long retention time (4000s)

Inexpensive

Simple fabrication

Lightweight


19/21


20/21


21/21

high voltage organic non-volatilte thin film

Documents