Diamond:H/Transition Metal Oxides Transfer-Doping: Efficiency and - - PowerPoint PPT Presentation

Diamond:H/Transition Metal Oxides Transfer-Doping: Efficiency and Transistor Performance

• Dr. Moshe Tordjman
• Prof. Rafi Kalish
• Prof. Jesus A. del Alamo
• Dr. Alon Vardi
• Dr. Zongyou Yin
• Dr. Youngtack Lee

Diamond Surface Transfer Doping with Adsorbates Molecules

Energy

‐4.2 eV NEA: ‐1.3 eV Diamond:H Adsorbate Acceptor

VB CB

f

E Chemical

f

Potential µ Vacuum Level

Energy

X [Å] Normal to Surface Diamond:H Adsorbate Acceptor

VB CB Chemical

f

Potential µ

f

E DHG 2

X [Å] Normal to Surface After Equilibrium State Before Electron Transfer

Drawbacks:

• 1. Volatile and Sensitive to Atmospheric

Fluctuations.

• 2. No Temperature Stability.
• 3. Low Work Function Limited conductivity

e‐ φ~ 4.2eV

Strobel et.al Nature,430, (2004) ;

• W. Chen, Prog. Surf. Sci (2009)

Diamond Surface Transfer Doping with Transition Metal Oxides

Energy

‐4.2 eV Diamond:H

VB CB

f

E

Energy

X [Å] Normal to Surface Diamond:H TMO Surface Acceptor

VBM CBM

f

E DHG 2

X [Å] Normal to Surface After Equilibrium State Before Electron Transfer

e‐ φ> 6.7eV s Surface Acceptors: TMO

f

E VB CB VB CB

f

E

TMO Surface Acceptor

Advantages:

• 1. Temperature Stability (up to 350-450C).
• 2. Higher Work function  Higher conductivity.

NEA: ‐1.3 eV

Vacuum Level

Tordjman et. al. Advanced Materials Interfaces , 20130 0155, (2014).

Diamond (100) Diamond:H Diamond:H Diamond:H

Hydrogen Plasma

In Situ Anneal 350˚C + Thermal Evaporation

3

MoO Van‐Der‐Paw Contacts Hall effect meas.

Simplified Structure Measurement

Diamond:H/TMO Transfer Doping

Acids Cleaning

TMOs come into Various:

• 1. Crystallization Structures.
• 2. Oxidation phases. (i.e. MoO3-x, V2O5-x , WO3-x etc..)
• 3. Coverage Uniformity.

TMO TMO Tordjman et.al. Appl. Phys. Lett.111, 111601 (2017)

MoO3 Thermal Evaporation Integrity to FET Fabrication Process

Diamond:H Diamond:H

Thermal dep.

3

MoO S/D Contacts E‐Beam

Diamond:H

C  150 Oxide gates ALD –

2

HfO

Diamond:H

Low Budget Temp. FET Fab. Process Challenges:

• 1. Nonhomogeneous Morphology.
• 2. Stoichiometry Changed by Fab. Process.
• 3. Carrier Loss due to band-energy Misalignment.

eV 5  eV 6.7 : 

Ra=0.86nm

2 ‐

cm

14

10 x 1 =

s

P

2 ‐

cm

12

10 x 4 =

s

P

Vardi et.al. EDL .35,12 (2014)

ALD 170C: Mo(CO)6 / O3  MoO3

 Roughness Quality improved.

• 1. Electronic Gap- States- reducing WF .
• 2. Band Energy Misalignment.

ALD MoO3 Surface Acceptor

Ra=0.36nm

Yin & Tordjman et. al. Science Advances, 4:eaau0480,(2018).

ALD 350C: C12H20MoN4 / H2O HyMoO3

O1s XPS Mo3d XPS

ALD HyMoO3 Surface Acceptor

Yin & Tordjman et. al. Science Advances, 4:eaau0480,(2018).

3

MoO

3

MoO

3

MoO

Y

H

3

MoO

Y

H

ALD 350C: C12H20MoN4 / H2O HyMoO3

ALD HyMoO3 Surface Acceptor

Yin & Tordjman et. al. Science Advances, 4:eaau0480,(2018).

Ra=0.30nm Hydrogen Incorporation Contributes:

• 1. Strengthen Covalent bonds.

 No O Reduction.  No Work Function Degradation.

• 2. Improved Surface Roughness Quality.
• What about Energy- Band Alignment?

Diamond:H/MoO3 Vs. HyMoO3 Properties

Diamond:H Diamond:H

ALD

3

MoO

y

H

• r

3

MoO S/D Contacts E‐Beam

Diamond:H

C  150 Oxide gates ALD –

2

HfO C  600 RTA +

Diamond:H

High Budget Temp. FET Fab. Process

Top gate + Channel isolation

5 10 15 20 25 30 35 40 45 50 55 60 65

MoO3-x ALD after process HyMoO3-x ALD after RTA As grown HyMoO3 ALD

2()

As grown MoO3 ALD HyMoO3-x

HyMoO3 MoO3-x MoO3

Intensity A.U

Mo3d XPS XRD Yin & Tordjman et. al. Science Advances, 4:eaau0480,(2018).

Diamond:H/MoO3 Vs. HyMoO3 FETs

Yin & Tordjman et. al. Science Advances, 4:eaau0480,(2018). 3

MoO

y

H

3

MoO

MoO3 Vs. HyMoO3 Band-Energy Alignment

Yin & Tordjman et. al. Science Advances, 4:eaau0480,(2018).

eV 5  eV 6.7 :  eV 5.9  eV 6 : 

3

MoO

y

H

3

MoO

MoO3 Vs. HyMoO3 Band-Energy Alignment

Yin & Tordjman et. al. Science Advances, 4:eaau0480,(2018).

Conclusions

• A Novel Advantageous Surface Acceptor: HyTMO
• General Strategy for Integrating and Modulating Electronic States in HyTMO.
• Diamond:H/HyMoO3 Surface Acceptor shows:

1. Improved Morphology Smoothness. 2. Immunity to Harsh Processing FET Fab. 3. Improved Cross‐Transport via band‐energy alignment.

Thank YoU