ph427 journal club presentation matt w. graham march 3, 2015 ph427 journal club presentation matt w....

PH427 Journal Club Presentation Matt W. Graham

March 3, 2015

PH427 Journal Club Presentation Matt W. Graham

March 3, 2015

Motivation

E(k)

Te

Th

T. Mueller et al., Nature Photonics 4, 297-301

(2010).

Graphene Photodetector

Fundamental Physics• How do electrons in graphene loose their energy?

Possible applications• graphene bolometers and photosensors• designing graphene electronics

< 4 meVfv

How do electrons relax in graphene?

2

00 meV 1/100s

f

v

v

Acoustic phonons or optical phonons?

< 4 meVfv

Relationship with class materialHow do electrons relax in graphene?

200

meV 1/100s

f

v

v

Acoustic phonons or optical phonons?

200 meV

kBTe

Supercollision acoustic phonon relaxation

qac vs

qdisorder

kBTeFast

0 5 10 40 801

10

100

SC predictionTra

nsie

nt P

hot

ocu

rren

t (p

A)

Time Delay (ps)

Tl=10 K

55 K 120 K 295 K

Result From Paper: supercollison acoustic model predict how electrons relax

3 3 /ee l e

dTA T T T

dt

/

1

1B ee k Tn

e

Conclusions: a new model and physical process of how electrons relax in graphene has been developed