LIEBER, Charles, Whither Nanotechnology, Harvard, Apr 1, 2013

this is a memorial lecture:  The John Stauffer Lecture.
This is at 4:15PM in Braun Auditorium (Chem); Monday.

Second part (which I must miss) will be on Wednes Apr 3 at 4:15P
on nanoelectronics in biology.

Introduction by Prof. Hongjie Dai (Chemistry):

His most important contrib is  Nanowires!  he created this field.
got his PhD at Stanford then postdoc at CalTech.

at Harvard since 1991.

interface nanowires with  neurons, etc.
Many, many prizes:  Gibbs, Wolf, ACS, World Tech, Sci Am,  Feynman Prize,  NSF.
NAS member.  Co-Editor of  Nano Letters
340 pubs,  35 patents;  founded  companies:  Nanosys,  Vista Therapeutics, and
nucleated  Nantero.  Piano, wrestler.
grew a 1700 lb pumpkin.
nickname  is Charlie;
****************************

his start:  this will be a general lecture:

first slide: acknowledges his students and collabs:

Key intro concepts:

NANOTECH:  his defn:  one dimension of object is < 100 nanos.  = nm

he also  refers to molecules,  quantum dots, viruses, subcell components:

many phsyical properties change as objects get smaller 

nanoscale is a natural  limit: down to one atom or to one molecule;  intrinsically binary

unexpected science and tech properties;
this field is intrinsically interdiscplinary...

novel phenomena at nano size...

Top-down paradigm: conventional nanoelectronics

We do not want to compete with Silicon Valley  but is there another way?
(Silicon Valley: starts with  growth of high purity silicon single crystals;  etc.  that drive Moore's Law:
lithography based)

in contrast:  Nanotech:  Bottom-up

example he shows his kids:  shows cute pic with his girl at age 6 and boy at age 12 or so
now girl is age 12 and has cut her hair and dyed it purple hair... is sophmore in college...
started from single cells: bottom-up growth;

example 2:  synthesis rather than lithography:
go UP from nanowires, nanoclusters to devices and from circuits to integr electronics..

promise is that we can  TUNE  the composition and structure of our devices on many length scales
which will lead to new  breakthrus...

CNTs = carbon nanotubes..

Prof. Iijima:  first detailed and unambig  struc analysis  of CNTs in 1991.
he discovered them.

"you have to MAKE your luck" he says.

history and discovery of GRAPHENE  Geim and coworkers   Nobel in Physics.

nano WHISKERS:  Wagner and Ellis in 1964 (long, tubular, grown structures)

Nanowire History; Key growth concepts...

he shows that the minimum diameter for a long time of a whisker was > 200 nm  cuz it
was dominated by  sigma(LV)  liquid-vapor interface free energy..

breakthru was in 1997
pub in 1998  Morales and Lieber... how to grow nanoscale wires...

create   saturated liquid dropletst  via  supersaturation/nucleation  leads to growth.

then development was rapid:.

got  functional nanowire building blocks

led to design and synthetic control of struc and compositon on many length scales by varying dopants etc.

2002 Lauhon,  Nature  grew coaxial cables

2011  make  3d  dendromers,  pub  in PNAS  Jiang  2011

Tian  2009  can introduce  stereo centers
Tian 2009 in Nat Nanotech  

****  uses for these***********

example 1:  (something everybody gave up on after this)  Nanocircuits

look at state of this in 2001  there were cover stories... full of promise/ hype.

he shows  PMOS Inverter  (NOR)  and can make a ring oscillator from these;
see Dekker...  Science 294, 1313 2001
only oscillated at 5 Hz  (but give us a break! this was back in 2001)

he then showed a  Half Adder;  Huang  Science 2001 above
and also  Lu (Wei)  and Lieber  Nat Mater in 2007

could make  integrated nanoelectronics... he mainly studies  crossed nanostruc ARRAYS...

but... big challenges:  at each cross point (each junction)  properties must be exactly the same
(and without  lithography)

slide:  configurable junctions:

but if M row wires and N column wires  then its  really a lot less detailed info storage then an
doing arbitary  M by N  array   (cuz, cannot simultaneously address, eg, two columns on a single row and v v s)

core shell

Ge/Si  core/shell nanowires as p-type semiconductor channel...

can also make variable oxide dielectric..
out of Al2O3...

can differentiate a junction  (he shows a hysteresis loop)  
(importantly, one half of loop is in the OFF voltage range) 

how to make an ALU out of this...

how to do Full Adder Circuit...
trivial by litho
BUT  S. Das at MITRE did this  entirely out of Nanowire junction array
(out of a switchable transistor)

eg  Ali Javey at Cal Berk.

shear-force-assisted printing of nanoscale wires...

he shows  a  couple cm size chip  that works! (made of nanowire arrays)

see Yan, Lieber  Nature 2011 (470,240, 2011)

programmable nonvolatile nanotransistor arrays

can also make a D-latch  (with feedback and  full subtractor and Mux/Demux...

can re-program one single array to do all these...

key challenges;  input/output matching  (cuz  diffs in ??  circuit params)

next... Nanocombing:  highly aligned and controlled organization

just do what you do when you comb your hair...
 need it anchored to your scalp and stretch it out with adhesive layer...
Yao, Yan and Lieber, Nat Nanotech...

with this  technique (anchoring and stretching via adhesion) get 
98.5% of nanoscale wires are aligned within + or - 1 degree!!!
10 fold improvement over existing methods

high degree of alignment...

deteministic nanocombing

1)  patterned  anchoring  sites define  lateral registry (spacing) and 
they also anchor one end of the nanowire...

2)  once stretched out, then can anchor other end of wire with a contact.

now can do  FSM = finite state machine:  a true nanoprocessor...

FSM is a model for computation
each circle denotes a 2-bit state
eg can do a flip flop with this which
changes state with each rising edge of the clock...

do this all with Ge/Si nanowries..

do with interconnects with litho...

he shows a 3 tile, 6-block  crossbar  implementation of the FSM  involving  8 feedback loops

2001  at 1-2 transistors
at 2010  were at adders etc.
now in 2013  possibility of standalone processors  FSM 2013.

looking to future:
2D cascaded  nanoprocessor

obvious applic:  polymeric substrate:  to  hybridize  with biologic tissues...
(here he is transitioning to what will be his main focus on Wed April 3rd 2013: Part 2)

***

Nanoelectronic biosensors:

for   real-time monitorng of patients eg

see eg  Cui (Yi), Lieber  in Science 1001   a bio-nanowire device interface...

can detect single viral particles !!!  PNAS 2004  in Zheng, Patolsky, Lieber...

Cancer Marker Protein detection...

leading company is QuantuMDx  point of care  DNA analys for rapid dx..

Vista Therapeutics.. monitoring of biomarkers of therap response and toxicity...

how to get into a cell

he shows a kinked nanorwire intracellular probe  going into a cell
(the largest advance OVER the patch clamp in decades)
will show in detail during Wednes talk..

*****

PHOTOVOLTAICS

fundamental science:  charge separation and recombo, light absorp:

but also non-fundamental:  eg  lowering manufac costs...

controlled synthesis of modulated nanowires...
switch dopant during growth so that eg first half is  P type and second half is  N type so
u get a junction...
get diode rectification...

Look at Tom Kempa work  in PNAS 2012..
concentric  nanowries:  can selectively etch off outer shells to
make contacts with interior  cylinders of the cable.

can also get  Unique and Tunable  light absorption
suggesting method of improving effic of  ultrathin  photovoltaics

can enhance  light absorption...
structure yeilds  100% higher over thin-film equivalent thickness...

huge improvement! (in efficiency of energy capture)

see Kim, Day, Lieber in Nano Letter 12, 4971 (2012)...

pushing synthesis to a new level:  Tom Kempa:
change size of facets of nanowries  (changing hexagonal x-section to 
change size of some of the facets)

can etch with H2O2  to produce nanochannels...  then fill channels with
catalysts, absorbers etc...

final slides:

Deep Blue (computer  goes to interface goes to a human brain)

he then shows a rat roving around outside in a field  with a (David Tank style)  brain interface..

so how do u seemlessly merge  electronics and tissue

now intro to  Wednes talk...

what he wants is  biologic function (cells) integrated into  electically activated implants

3d  nanoelectronic extracellular matrix and then from that
make a 3d  nanoelectr synthetic tissue  (to implant)
by embedding cells...

need macroporosity to make this work...

want 3d  scaffolds that have macro dimensions (> 1mm thickness and > cm size)
with embeded nanoelectornics...

he calls it Cyborg tissue...

he wants 3d neural tissue “innervated with 3d  nanoelectronics...

(subject of Wednes talk)
my Q1:  will nanowires be ready for Moore's Law:
his answer:  not trying to compete with litho...(appears to think
that Moore's law (litho CMOS) will continue a while longer...
his view is that this will be applied to entirely difft areas  (eg biosensors)

my Q2:   BAM (Obama State of the Union Brain Activity Map Project);
  prospects for funding and  prospects for success;?
A:  Discussed with a number of colleagues (opinions all over the map: same as my experience) do not know
He is not involved with that proposal.

Q:   why do wires stay aligned within one degree

I chat afterward with CL:  (very strong grip: ex-wrestler!)

Also chat with Dr Tad Hogg: resch fellow: Inst of Molec Manuf

and with Rod McCalley (Lockheed ATC)  (the 3 of us separately biked:
(great minds bike along similar paths!)