THE NATIONAL INSTITUTE OF ENGINEERING Department OF MECHANICAL ENGINEERING CENTRE FOR NANO-TECHNOLOGY MYSURU, KARNATAKA, india-570008 PROJECT REPORT ON Source/Drain Schottky Barrier Height(SBH) reduction by Metal-Insulator-Semiconductor(M-I-S) structure using TiO2 and HfO2 ultrathin dielectric insertion and barrier inhomogenity studies via Gaussian distribution model for Field Effect Transistor application PRESENTED BY INTERNAL GUIDE EXTERNAL GUIDE HARISHA C P Dr. SIDDHARTH JOSHI Dr. MING-HAN LIAO 4NI17INT02 ASSOCIATE PROFESSOR PROFESSOR IV SEMESTER, M.TECH CENTER FOR NANOTECHNOLOGY DEPT. OF MECHANICAL ENGG. NIE, MYSURU, INDIA NIE, MYSURU, INDIA NTU, TAIWAN (ROC)

Contents INTRODUCTION LITERATURE SURVEY OBJECTIVE AND METHODOLOGY ATOMIC LAYER DEPOSITION AND PRECURSORS THEORY BEHIND M-S CONTACTS THEORETICAL AND EXPERIEMNTAL DETAILS ELECTRICAL PROPERTIES SHOTTKY BARRIER HEIGHT EXTRACTION MODELS TEMPERATURE DEPENDANT I-V EXPERIMENTAL ANALYSIS POLARIZATION STUDIES ON BILAYER SAMPLES FUTURE WORK CONCLUSION REFERENCES DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Introduction Fermi Level Pinning (FLP) at Metal-Semiconductor is a major problem which results in high Schottky barrier for electrons. FLP origin is attributed to the Metal Induced Gap States (MIGS) or bond polarization in addition to the physical non idealities of the interface such as dangling bonds. This Schottky barrier can be modulated by inserting a ultrathin dielectric between metal and semiconductor. This dielectric layer between metal and semiconductor helps to depin the Fermi Level. The present work is to experimentally demonstrate how an intermediate TiO2 and HfO2 affects the carrier transport mechanism and SBH. DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Introduction ECB ϕb EFM EVB EG (b) P-Type Semiconductor (a) N-Type Semiconductor ϕb EFM EG ECB EVB Figure 1: Band diagrams for (a) n-type and (b) p-type metal-semiconductor junction at zero bias (equilibrium). DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Introduction ϕb EFM (b) M-I-S Contact with high-K dielectric (a) Traditional M-S Contact ϕb EFM Large FLP MIGS Polarization dipoles Metal Semiconductor Less FLP High-K dielectric Thermionic barrier Tunnel barrier MIGS reduced Figure 2: (a) The origin of FLP in the M-S junction (b) M-I-S contact system characterized by Fermi level depinning and lower Φb. DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Fig 3: Contact resistance Vs insulator thickness Introduction Fig 3: Contact resistance Vs insulator thickness Hu, Saraswat, and Wong Appl. Phys. Lett. 99, 092107 (2011) DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Literature Survey 1. The influence of Fermi level pinning/depinning on the Schottky barrier height and contact resistance in Ge/CoFeB and Ge/MgO/CoFeB structures. Lee et al. Appl. Phys. Lett. 96, 052514 (2010) 2. Metal/III-V effective barrier height tuning using atomic layer deposition of high-κ/high-κ bilayer interfaces. Hu, Saraswat, and Wong Appl. Phys. Lett. 99, 092107 (2011) 3. Mechanism of Schottky barrier height modulation by thin dielectric insertion on n-type germanium. B.-Y. Tsui and M.-H. Kao Appl. Phys. Lett. 103, 032104 (2013) 4. Alleviation of Fermi-level pinning effect on metal/germanium interface by insertion of an ultrathin aluminum oxide. Zhou et al. Appl. Phys. Lett. 93, 202105 (2008) 5. The comprehensive study and the reduction of contact resistivity on the n-InGaAs M-I-S contact system with different inserted insulators. M.-H.Liao and C.Lien AIP Advances5,057117(2015) 6. Fermi level depinning and contact resistivity reduction using a reduced titania interlayer in n-silicon metal-insulator-semiconductor ohmic contacts. Agrawal et al. Appl. Phys. Lett. 104, 112101 (2014) DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Literature Survey 7. Experimental demonstration on the ultra-low source/drain resistance by metal-insulator-semiconductor contact structure in In0.53Ga0.47As field effect transistors. M.-H. Liao and P.-K. Chen AIP Advances 3, 092118 (2013) 8. Experimental demonstration for the implant-free In0.53Ga0.47As quantum well metal-insulator-semiconductor field-effect transistors with ultra-low source/drain resistance. M.-H. Liao and L. C. Chang Appl. Phys. Lett. 103, 072102 (2013) 9. Contact resistivities of metal-insulator-semiconductor contacts and metalsemiconductor contacts. Yu et al. Appl. Phys. Lett. 108, 171602 (2016) 10. Reduced Contact Resistance Between Metal and n-Ge by Insertion of ZnO with Argon Plasma Treatment. Zhang et al. Nanoscale Research Letters (2018) 11. Effective Schottky Barrier Height Lowering of Metal/n-Ge with a TiO2/ GeO2 Interlayer Stack. Gwang-Sik Kim, Sun-Woo Kim, Seung-Hwan Kim, June Park, Yujin Seo, Byung Jin Cho, Changhwan Shin, Joon Hyung Shim, and Hyun-Yong Yu; ACS Appl. Mater. Interfaces 2016, 8, 35419−35425 DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Literature Survey 12. Schottky barrier height reduction for metal/n-InP by inserting ultra-thin atomic layer deposited high-k dielectrics. Zheng et al. Appl. Phys. Lett. 103, 261602 (2013) 13. Analysis of the Inhomogeneous Barrier in In/p-Si Schottky Contact and Modified Richardson Plot. J.M. DHIMMAR, H.N. DESAI, B.P. MODI J. NANO- ELECTRON. PHYS. 8, 02006 (2016) 14. Temperature dependent electrical characterisation of Pt/HfO2/n-GaN metal-insulatorsemiconductor (MIS) Schottky diodes. Shettyetal. AIPAdvances5,097103(2015) 15. Schottky barrier height extraction from forward current-voltage characteristics of nonideal diodes with high series resistance. K. Ahmed and T. Chiang Appl. Phys. Lett. 102, 042110 (2013) 16. Effect of atomically controlled interfaces on Fermi-level pinning at metal/Ge interfaces. Yamane et al. Appl. Phys. Lett. 96, 162104 (2010) 17. Temperature Dependency of Schottky Barrier Parameters of Ti Schottky Contacts to Si-on-Insulator. I. Jyothi et al; Materials Transactions, Vol. 54, No. 9 (2013) pp. 1655 to 1660 ©2013 The Japan Institute of Metals and Materials DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Literature Survey 18. Mean Barrier Height and Richardson Constant for Pd/ZnO Thin Film-Based Schottky Diodes Grown on n-Si Substrates by Thermal Evaporation Method. Divya Somvanshi and Satyabrata Jit; IEEE ELECTRON DEVICE LETTERS, VOL. 34, NO. 10, OCTOBER 2013 19. Schottky Barrier Height Engineering for Electrical Contacts of Multilayered MoS2 Transistors with Reduction of Metal-Induced Gap States. Gwang-Sik Kim, Seung-Hwan Kim, June Park, Kyu Hyun Han, Jiyoung Kim, and Hyun-Yong Yu; ACS Nano 2018, 12, 6292−6300 20. The Richardson constant and barrier inhomogeneity at Au/Si3N4/n-Si (MIS) Schottky diodes. A Tataro˘glu and F Z P¨ur; Phys. Scr. 88 (2013) 015801 21. A text book on “Semiconductor Physical Electronics” by Sheng S. Li 22. A text book on “Physics of Semiconductor Devices” by S. M. Sze and Kwok K. Ng 23. A text book on “Semiconductor Physics and Devices” by Donald A. Neamen 24. A text book on “Semiconductor device fundamentals” by Robert F. Pierret 25. A text book on “Semiconductor Devices: Theory and Application” by James M. Fiore 26. A text book on “Understanding Semiconductor Devices” by Sima Dimitrijev DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Objective and Methodology M-I-S Contact Structure Semiconductor Ultrathin Dielectric Thin Metal Tunneling Ohmic Contact Figure 4: Schematic diagram of M-I-S diode and tunneling through insulator DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Objective and Methodology SBH reduction mechanisms by thin dielectric layer To reduce MIGS by blocking electron wave function from metal to semiconductor (MIGS model) Dipole formed at Metal/Semiconductor interface would cause potential drop to alleviate SBH (Dipole model) Fixed charges in dielectric layer would also cause extra potential drop (Fixed charge model) Figure 5: Mechanisms of SBH reduction. DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Objective and Methodology By Egun By Sputtering By ALD Semiconductor (n-type and p-type) TiO2 and HfO2 (3nm, 2nm and 1nm) and bilayer Pt (100nm) Ohmic Contact Semiconductor (n-type and p-type) TiO2 and HfO2 (3nm, 2nm and 1nm) and bilayer Al (100nm) Ohmic Contact Figure 6: Schematic diagram of M-I-S diode in this work Contact Area : 0.125664cm2 using shadow mask DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Objective and Methodology Wafer details Sl. No. Details N-Type P-Type 1 Dopant Phosphorous Boron 2 Doping Concentration 1 ͂ 2X1016 /cm3 2 ͂ 6X1014/cm3 3 Resistivity 1-10 Ω-cm 11-14 Ω-cm 4 Crystal Orientation <100> DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Objective and Methodology Wafer cleaning procedure Acetone Alcohol DI Water DHF (50:1) DI Water DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Atomic Layer Deposition & Precursors Study on TiO2 deposition by ALD Precursor 1:Tetrakis(dimethylamino)titanium (TDMAT) Precursor 2: H2O Chamber Temperature : 250⁰C Base pressure : 7E-3 torr Working Pressure : 4.3 torr Precursor temperature: 65 ⁰C Precursor line temperature: 90 ⁰C DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Atomic Layer Deposition & Precursors Study on HfO2 deposition by ALD Precursor 1: Tetrakis(ethylmethylamino)hafnium(IV) (TEMAH) Precursor 2: H2O Chamber Temperature : 300⁰C Base pressure : 4E-2 torr Working Pressure : 2.0 torr Precursor temperature: 60 ⁰C Precursor line temperature: 120 ⁰C DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Atomic Layer Deposition & Precursors Sl. No. Technical parameters TiO2 HfO2 1 Band gap 3.5eV 5.8eV 2 Electron affinity 4.15+/-0.25eV 2.5+/-0.25eV 3 Conduction band offset 1.4 4 Dielectric constant 80 25 DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Theory behind M-S contacts Electrical nature of Ideal MS contacts Where, ՓM = Metal Work function ՓS = Semiconductor Work function Source: Semiconductor Device fundamentals by Robert F. Pierret DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Theory behind M-S contacts According to the Schottky–Mott relation: SBH can be calculated as follows : For an ideal Schottky contact to an n-type semiconductor : For an ideal Schottky contact on p-type semiconductor : Where, ՓB= Schottky Barrier Height ՓM = Metal Work function Eg = Semiconductor band gap χ = Electron affinity of semiconductor Source: Semiconductor Device fundamentals by Robert F. Pierret DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Theory behind M-S contacts For an ideal Schottky contact on n-type semiconductor : 1) Using Pt as electrode : ՓB= ՓM- χ = 5.65-4.05= 1.6eV 1) Using Al as electrode : ՓB= ՓM- χ = 4.28-4.05= 0.23eV Source: Work function values are from Journal of Applied Physics, Vol. 48, No. 11, November 1977 DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Theory behind M-S contacts For an ideal Schottky contact on p-type semiconductor : 1) Using Pt as electrode : ՓB= Eg+ χ- ՓM= 1.1+4.05-5.65= -0.5eV 1) Using Al as electrode : ՓB= Eg+ χ- ՓM= 1.1+4.05-4.28= 0.87eV Source: Work function values are from Journal of Applied Physics, Vol. 48, No. 11, November 1977 DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Theoretical and Experimental details Semiconductor Metal Theoretical SBH Theoretical contact type Our experimental observation based on I-V n-Si Pt 1.6 eV Schottky/Rectifying Al 0.23 eV Semi-Ohmic/non-rectifying p-Si -0.5 eV Ohmic/non-rectifying 0.87 eV DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Experimental details Semiconductor Metal Single Layer HfO2 Single Layer TiO2 Bi-layer HfO2/TiO2 Bi-layer TiO2/HfO2 n-Si Pt 3nm, 2nm and 1nm 1nm each Al p-Si M-S structure DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Electrical Properties M-S and M-I-S structures comparison on n-Si Increase in reverse current Reduction of SBH Enhances the TE More carriers emitted from metal to SC. Semiconductor (n-type Si) TiO2 (3nm, 2nm and 1nm) and bilayer Pt (100nm) Ohmic Contact Conclusion : Indication of Schottky to Ohmic conversion. DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Electrical Properties M-S and M-I-S structures comparison on n-Si Increase in reverse current Reduction of SBH Enhances the TE More carriers emitted from metal to SC. Semiconductor (n-type Si) HfO2 (3nm, 2nm and 1nm) and bilayer Pt (100nm) Ohmic Contact Conclusion : Indication of Schottky to Ohmic conversion. DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Electrical Properties M-S and M-I-S structures comparison on n-Si Reverse current remains unchanged. Carriers can tunnel through the interfacial dielectric layer. Semiconductor (n-type Si) TiO2 (3nm, 2nm and 1nm) and bilayer Al (100nm) Ohmic Contact Conclusion : Ohmic nature retained. DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Electrical Properties M-S and M-I-S structures comparison on n-Si Small reduction in reverse current Large tunnel barrier effect. Semiconductor (n-type Si) HfO2 (3nm, 2nm and 1nm) and bilayer Al (100nm) Ohmic Contact Conclusion : Ohmic nature retained. DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Electrical Properties M-S and M-I-S structures comparison on p-Si Small increase in both forward and reverse current Carriers can tunnel through the interfacial layer along with Thermionic emission Semiconductor (p-type Si) TiO2 (3nm, 2nm and 1nm) and bilayer Pt (100nm) Ohmic Contact Conclusion : A small improvement in Ohmic nature. DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Electrical Properties M-S and M-I-S structures comparison on p-Si Considerable increase in both forward and reverse current Carriers can tunnel through the interfacial layer along with Thermionic emission Semiconductor (p-type Si) HfO2 (3nm, 2nm and 1nm) and bilayer Pt (100nm) Ohmic Contact Conclusion : A considerable improvement in Ohmic nature. DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Electrical Properties M-S and M-I-S structures comparison on p-Si Decrease in forward current with TiO2 insertion and bilayer insertion Semiconductor (p-type Si) TiO2 (3nm, 2nm and 1nm) and bilayer Al (100nm) Ohmic Contact Conclusion : Indication of Schottky to Ohmic conversion??? DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Electrical Properties M-S and M-I-S structures comparison on p-Si Decrease in forward current with HfO2 insertion and bilayer insertion Semiconductor (p-type Si) HfO2 (3nm, 2nm and 1nm) and bilayer Al(100nm) Ohmic Contact Conclusion : Indication of Schottky to Ohmic conversion??? DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

SBH Extraction (J-V Model) The J-V relation for a Schottky diode under the forward bias (qV>3kT) is given by Where, J0 =saturation current density n = ideality factor V=forward bias voltage T=Temperature q= Electron charge k= Boltzmann constant ՓB0= Apparent SBH at zero bias A*= Richardson constant A* for p-Si=32A/cm2K2 and for n-Si=112A/cm2K2 Step 1: ln(J) Vs V plot Step 2: Slope=q/nkT and intercept at V=0 is J0 (forward bias) Using this value in the above equation, ՓB can be deduced. DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

SBH Extraction (Thermionic Emission Model) To take care of the uncertainty of the Richardson constant and the effective diode area, we consider I-V-T method under reverse bias, Step 1: produce ln(J0/T2) Vs 1000/T (Richardson plot) (Reverse bias) Step 2 : Slope=-qՓB/k and intercept on the ordinate gives A* ( effective Richardson constant) The J-V relation of a Schottky diode with a thin interfacial insulator in between the metal and semiconductor is given by Where is the tunneling probability, which can be considered as a modification to the effective Richardson constant A*. (For M-S contact) (For M-I-S contact) DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

SBH Extraction (Gauss Distribution Model) This model takes the surface inhomogeneities into account by assuming that the Schottky barrier exhibits a Gaussian distribution profile over the contact area. The Gaussian distribution of barrier heights can be expressed by the following equation: A linear fit on the plot of Փap versus q/2kT gives, y-axis intercept gives us the value of zero bias barrier height Փb0. The slope of the line gives the value of standard deviation σ2. Finally inhomogeneities in the barrier height are accounted for in the modified Richardson’s plot as per the below equation. DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Temperature dependant I-V(I-V-T) Pt/n-Si (M-S) Contact This case is very important as it is a Schottky contact SBH based on room temperature I-V=0.71eV Note : Schottky nature at room temperature. DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Richardson plot and SBH extraction(TE model) Pt/n-Si (M-S) Contact Conventional Richardson plot y = -0.537x - 7.132 SBH, ՓB = 0.53eV Richardson Constant A*= 6.35X10-3Acm-2K-2 DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Richardson plot and SBH extraction(GD model) Pt/n-Si (M-S) Contact Temperature T (K) Barrier Height ՓB (eV) 298 0.6239 318 0.6649 338 0.6973 358 0.8247 378 0.8896 We observe that SBH increases from 0.62eV to 0.88eV as the temperature is increased from 298K to 378K. DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Richardson plot and SBH extraction(GD model) Pt/n-Si (M-S) Contact Zero bias SBH, ՓB0=1.882 eV Standard deviation, σs2= 0.066V y = -0.066x + 1.882 DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Richardson plot and SBH extraction(GD model) Pt/n-Si (M-S) Contact Modified Richardson plot y = -1.798x - 0.408 SBH, ՓB = 1.80eV Richardson Constant A*= 5.29Acm-2K-2 DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Temperature dependant I-V(I-V-T) Pt/HfO2(3nm)/n-Si (M-I-S) Contact SBH based on room temperature I-V=0.59eV Note : Schottky nature at room temperature. DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Richardson plot and SBH extraction(TE model) Pt/HfO2(3nm)/n-Si (M-I-S) Contact Conventional Richardson plot y = -0.425x - 12.98 SBH, ՓB = 0.425eV Richardson Constant A*= 1.83X10-5Acm-2K-2 DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Richardson plot and SBH extraction(GD model) Pt/HfO2(3nm)/n-Si (M-I-S) Contact Temperature T (K) Barrier Height ՓB (eV) 298 0.6565 318 0.7556 338 0.7674 358 0.8123 378 0.8602 We observe that SBH increases from 0.65eV to 0.86eV as the temperature is increased from 298K to 378K. DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Richardson plot and SBH extraction(GD model) Pt/HfO2(3nm)/n-Si (M-I-S) Contact Zero bias SBH, ՓB0= 1.55eV Standard deviation, σs2= 0.045V y = -0.045x + 1.554 DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Richardson plot and SBH extraction(GD model) Pt/HfO2(3nm)/n-Si (M-I-S) Contact Modified Richardson plot y = -1.536x + 2.265 SBH, ՓB = 1.53eV Richardson Constant A*= 76.64Acm-2K-2 DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Summary of SBH Model Pt/n-Si Pt/HfO2(3nm)/n-Si Schottky-Mott rule 1.6eV - Room temperature J-V model (Forward bias) 0.71eV 0.59eV Thermionic Emission model (Reverse bias) (Conventional Richardson plot) 0.53eV 0.42eV Thermionic Emission with Gauss Distribution model (Forward bias) (Based on apparent SBH) 1.88eV 1.55eV Gauss Distribution model )(Forward bias) (Modified Richardson plot 1.80eV 1.53eV DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Temperature dependant I-V(I-V-T) Pt/p-Si (M-S) Contact SBH based on room temperature I-V=0.56eV Note : Ohmic nature at room temperature. DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Richardson plot and SBH extraction(TE model) Pt/p-Si (M-S) Contact y = -0.18x - 17.99 Conventional Richardson plot SBH, ՓB = 0.18eV Richardson Constant A*= 1.22X10-7Acm-2K-2 DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Richardson plot and SBH extraction(GD model) Pt/n-Si (M-S) Contact Temperature T (K) Barrier Height ՓB (eV) 298 0.5779 318 0.5959 338 0.6140 358 0.7197 378 0.7507 We observe that SBH increases from 0.57eV to 0.75eV as the temperature is increased from 298K to 378K. DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Richardson plot and SBH extraction(GD model) Pt/n-Si (M-S) Contact Zero bias SBH, ՓB0=1.42eV Standard deviation, σs2= 0.044V y = -0.044x + 1.425 DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Richardson plot and SBH extraction(GD model) Pt/n-Si (M-S) Contact Modified Richardson plot y = -1.230x - 1.838 SBH, ՓB = 1.23eV Richardson Constant A*= 1.2663Acm-2K-2 DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Polarization studies on bilayer samples EFM EG ECB EVB Metal n-Si Metal Insulator n-Si Metal Insulator1 Insulator2 n-Si Tunneling current (a) (b) (c) Figure 7 : Schematic band diagram of a pinned Fermi level and depinning with single and double dielectric layers DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Polarization studies on bilayer samples Measurement condition Applied Voltage : 5V Applied field : 25000kV/cm Hysteresis period : 100ms Frequency : 1.00X101 Hz P max=30.952 P max=3.768 DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Polarization studies on bilayer samples Measurement condition Applied Voltage : 5V Applied field : 25000kV/cm Hysteresis period : 100ms Frequency : 1.00X101 Hz P max=4.839 P max=89.864 DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANO-TECHNOLOGY, NIE , MYSURU.

Future work Completing I-V-T measurement and extracting SBH for other samples. XPS studies will be carried out in order to understand the TiO2 and HfO2 stoichiometry and the physics behind the interface. Polarization studies will be conducted to understand the contribution of dipole density towards MIGS reduction and leakage phenomena will be analyzed in comparison with C-V curves. The in-situ annealing will be carried out in ALD chamber at various temperatures (if time permits). DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANOTECHNOLOGY, NIE MYSURU

DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANOTECHNOLOGY, NIE MYSURU Conclusion We found that, the M-I-S structures can have reduced SBH and thus can yield lower contact resistance at source/drain region. The thickness of the interfacial insulator is found to be a critical factor. We found to have distorted P-E curves for M-I-S structures due to high leakage current. But, the polarization values are still considerable which is the clear indication of dipole formation at high-k/high-k interface. Which needs further investigation through C-V curves at same frequency levels. The Gaussian distribution model gives the accurate value on SBH compared to J-V model and TE model. DEPARTMENT OF MECHANICAL ENGG., CENTRE FOR NANOTECHNOLOGY, NIE MYSURU

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