Presentacion Materiales Ferroeléctricos

8/20/2019 Presentacion Materiales Ferroeléctricos

1/20

Switchable Ferroelectric

Diode andPhotovoltaic Effect in

BiFeO3

(Science, Vol 329, April 29!

"o#e Antonio Pe$a %arcia

&art' %tierre) *atorre


2/20

Switchable Diode

Diode+ r-#talline piece with a p.n /nction connectedto two electrical ter0inal#

Switchable Diode+ the polarit- of the diode can bereprodcibl- #witched b- the rever#ion of the appliedelectric field


3/20

Photovoltaic Effect

1t i# the creation of voltae or electriccrrent in a 0aterial pon to epo#re toliht


4/20

&ain propertie# of ferroelectric#

4he- #witch the cr-#tal #trctre at a certain te0peratre

5ih #-00etr- (non ferroelectric!

6ever#ible

*ow #-00etr- (ferroelectric!

*ow #i00etr- enerate# polar direction#, hencepolari)ation

4he- 0aintain the polari)ation #tate in the ab#ence of avoltae and the po##ibilit- to rever#e the polari)ationdirection b- appl-in an electric field


5/20

&ain propertie# of ferroelectric#

4he- #how photocrrent when ill0inated, bt not li7e#e0icondctor# (and that8# the point!

4here8# onl- photocrrent in the polari)ation direction,the oriin i# #till nclear, bt it wor7#

Photocrrent den#it- i# low, bt it i# proportional to thelenth in the polari)ation #o it8# o7


6/20

BiFeO3Perov#7ite t-pe nit cell with

a:3;9< = and >:?9;3@

6ho0boedral #trctre (63c!

rie 4e0peratre+

Cel 4e0peratre+ .pha#e i# 0eta#table in air Vacc0 condition#


7/20

4hree BiFeO3 r-#tal# are #tdied

One ferroelectric do0ain, #a0e #pace di#po#ition,different thic7ne##e# (H, ? and 9I0!

JDia0eter.circlar thic7

Samples BFO thickness(μm)/A(mm2) Electrodes

BFO HK 22 AK ;< 00JBFO2 ?K 2;2; AK ;


8/20

Sa0ple#

A

BFO

A

BFO

A

A

BFO

BFO2

A

A

BFO

BFO3


9/20

Eperi0ent

Sa0ple+ AKBFOKAL Dar7 condition#

Fir#t the diodeli7e behavior and te0peratre effect are#tdied

ABFO

A

BFO


10/20

6e#lt#

Diodeli7e behavior i# ob#erved

rrent den#it- increa#e with 4e0peratre

6ectification ratio(6:"(E:M;3!K"(E:.;3! increa#e with4e0peratre

Polari)ation #witch doe# not occr

Temperature (K) Rectiication ratio

2 3

2 93 N??

3 N9


11/20

Eperi0ent 2

4he polari)ation direction clearl- ha# relevance

Pl#e#: V (E:H7VKc0!K t: ; #

PF&+ Vr0# and f:H 75)

A

A

BFO

BFO3


12/20

6e#lt#

Flip in the electric polari)ationafter .V pl#e#

4he diode forward and rever#e

direction# #witch when thedirection of P i# rever#erd

4he aplication of the #econd #et of M.V pl#e doe#not re#tore oriinal confiration


13/20

Eperi0ent 3

Sa0ple+ AKBFO2KAL %reen liht (:32 n0!

4hen the photocrrent i# #tdied

A (

A (

B F O

6iht*eft

A

A

BFO

BFO2


14/20

6e#lt#

Qhen a bia# potential i# applied to the 0aterial thephotocrrent follow# the bia#

Qhen there i# no bia#, it follow# the polari)ation direction,and i# alwa-# neative

*eft.#ide ill0ination wor7# better than riht.#ideill0ination

!llumination"side #hotocurrent($%&)' (μA)

Reerse $ias(μA/cm2)

*eft.#ide .;3 ?;29

6iht.#ide .;3 ;?N9


15/20

Eperi0ent N

4he #ide of the il0ination i# relevant beca#e thephotocrrent i# a##-0etric (de to ther0oelectricit-,probabl-R!

A

A

BFO

BFO2


16/20

6e#lt#

4he crrent withot liht decrea#ed to ; pA

Sa0e )ero.bia# photocrrent direction in both #ide#

&ch 0ore inten#e with hih ener- liht

Photovoltaic effect ha# been de0on#trated

6iht.left a#-00etr- 0a- re#lt fro0 a ther0oelectric

power effect andKor ncontrolled a#-00etrie# in theconfiration


17/20

Eperi0ent

4he anle between the #a0ple and Polari)er affect# too

Ble ircle#+ 1nitial po#ition

%reen ircle#+ 1nitial po#ition M polari)er rotation of 9@

A

A

BFO

BFO2


18/20

6e#lt#

4he PV effect i# 0ai00 when the polari)ed.lihtelectric field i# parallel to the in.plane co0ponent offerroelectric polari)ation (:9@!

4he PV effect i# 0ini00 when the polari)ed.lihtelectric field i# perpendiclar to the in.planeco0ponent of ferroelectric polari)ation (:@!

After the rotation b- 9@, the chane of photocrrent i#

#i0ilar, ecept for a 9@ pha#e


19/20

oncl#ion#

Diodeli7e behavior and Photovoltaic effect ha# been#hown

Qhen a electical field larer than the coercitive field i#applied the diode polari)ation #witche#

4he )ero bia# photocrrent den#it- i# #ide dependent


20/20

on#trctive critici#0

Are the #a0ple# trl- 0onodo0ain#T

10ae# cold be better eplained

1# the crrent den#it- proportional to lenthT

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Presentacion Materiales Ferroeléctricos