footer.jpg pic_titel_1.jpg eth_ologo CSEM-regular L-NESS-Logo 6 December 2012 Masaryk University, Brno Marriage Between Incompatible Couples: Mismatched Materials Claudiu V. Falub Laboratory for Solid State Physics ETH Zürich, Switzerland cfalub@phys.ethz.ch footer.jpg 2 c:\Users\Claudiu\Documents\Work-ETHZ\Logos\eth_logo_black.png http://www.3cx.de/blog/wp-content/uploads/2010/04/swissflag.gif Laboratory for Solid State Physics Thomas Kreiliger Alfonso G. Taboada Elisabeth Müller Hans von Känel Claudiu V. Falub Frontiers In Research: Space and Time 860 m2 Physics of New Materials http://www.pnm.ethz.ch Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 3 Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 4 Fabio Pezzoli Fabio Isa Daniel Chrastina Giovanni Isella Collaborations C:\Users\Claudiu\Documents\Work-ETHZ\Publications\ETHZ\CAS2012\clean.jpg L-NESS Roberto Bergamaschini Emiliano Bonera Leo Miglio Anna Marzegalli L-NESS: Laboratory for Epitaxial Nanostructures on Silicon and Spintronics (Como, Italy) Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 5 Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 6 Philippe Niedermann Antonia Neels Aurélie Pezous Rolf Kaufmann Alex Dommann http://www.3cx.de/blog/wp-content/uploads/2010/04/swissflag.gif Mojmir Meduňa Collaborations Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 7 Claudiu V. Falub, ETH Zürich 6 December 2012, Brno International Roadmap for Semiconductors footer.jpg 8 Motivation: Integrated Miniaturized X-ray Systems §Next Generation X-Ray Systems §High resolution/sensitivity §Ge as conversion layer §No bump-bonding (monolithic integration) “NEXRAY” Fast, programmable X-ray sources Ge layers for high-energy X-ray detection Single-photon solid-state X-ray detection Phase contrast X-ray imaging logo_empa_bl_ol [Converti] c:\Users\Claudiu\Documents\Work-ETHZ\Logos\eth_logo_black.png CSEM-regular http://www.nanotera.ch/images/mainlogo.gif Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 9 Motivation: Next Generation X-Ray Detectors 64´64 pixel IR sensor with integrated Ge photodiodes D = 100 mm For X-rays → SUPER THICK (> 50 mm !!!) high quality (i.e. dislocations, uniformity) Ge epilayers · Why Germanium? 2 mm · Monolithic integration of a 3 mm Ge film with CMOS for IR radiation was demonstrated at ETHZ/CSEM R. Kaufmann et al., J. Appl. Phys. 110, 023107 (2011) Ge Z=32 Si Z=14 Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 10 Integration of Mismatched Materials: State-of-the-art L Debonding may occur at large DT L Expensive bump-bonding required A. Wafer Bonding Diode Layer Connecting Bumps CMOS Layer Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 11 Integration of Mismatched Materials: State-of-the-art B. Monolithic Integration (HETERO-EPITAXY) Substrate Layer 1 Layer 2 Processed wafer Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 12 Key Problems of Hetero-Epitaxy exhibit_3.gif exhibit_3.gif exhibit_3.gif a=asub a>asub aa0 a0 a0 MDs TDs a1>a0 TDs – threading dislocations MDs – misfit dislocations Untitled-2 200 nm Ge TDs MDs Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 13 §S. Luryi, E. Suhir, APL 49, 140 (1986) → critical thickness increases very much with the reduction of the lateral dimension of the patterned areas (A) §E.A. Fitzgerald, N. Chand, J. Electron. Mater. 20, 839 (1991) → Epitaxial Necking (GaAs on Si) Fitzgerald_Amberwave.jpg (B) (B) §T.A. Langdo et al., APL 76, 3700 (2000) → Epitaxial Necking (Ge on Si) (C) (C) §J.S. Park et al., APL 90, 052113 (2007) → Aspect Ratio Trapping (ART) Dislocations Control by Substrate Patterning A.E. Blakeslee, MRS Symp. Proc. 148, 217 (1989) 60-degree dislocations J.W.Matthews et al., JAP 41, 3800 (1970) L h <100> (A) Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 14 Growth on Patterned Si Wafers Si “pilars” (DRIE) LEPECVD: “Low Energy Plasma Enhanced CVD” (H. von Känel, ETH-Zürich) 1 mm Ge Ge growth (~4 nm/s) (LEPECVD) 7 mm Ge Ge “towers” (Quenched Lateral Growth) Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 15 New Growth Mechanism: Self Limiting Lateral Growth Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 16 Unlimited Layer Thickness 10 mm Ge “towers”: 50 mm (!) · Cracks don’t propagate into the patterned area · Elimination of the wafer bowing Unpatterned area → Cracks Patterned area → No Cracks 100 mm thin pre-patterned 8” CMOS wafer completely covered with 20-mm-tall Ge towers → very small bowing! Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 17 Very High Surface Filling Ge “towers”: 50 mm (!) C:\Users\Claudiu\Documents\Work-ETHZ\XRD\ESRF\Beamtime-2012\SEM-10Sep\56693-D1-19.tif C:\Users\Claudiu\Desktop\wafer.png 8" wafer Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 18 Ubiquity of the Epitaxial Growth Mode Ge towers are obtained for different thermal/lattice mismatch, substrate miscut, geometry of the patterns (e.g. pillars, ridges), initial facet distribution (passivated or not), smootheness of the pillar sidewalls ! Si Passivated Si60Ge40 Ge Non-passivated Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 19 Growth of Germanium on Si Ridges Þ Growth of Ge on Si ridges is similar to that on Si pillars C:\Users\Claudiu\Documents\Work-ETHZ\SEM\56596\56596-G1-06.tif C:\Users\Claudiu\Documents\Work-ETHZ\SEM\56596\56596-H1-05.tif 3 mm 3 mm C:\Users\Claudiu\Documents\Work-ETHZ\SEM\56597\H1\56597-H1-02.tif 6 mm Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 20 Growth of Germanium on Si(111) substrates Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg From Isolated Pillars to Closely Spaced Pillar Array 21 2) Mutual flux shielding 1) High deposition rate (~ 4 nm/s) Þ Short diffusion length Modelling based on the rate equation for the adatom phase Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 22 Dislocation Management by Epitaxial Necking “60°Dislocations” “Growth Dislocations” Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 23 J. Bai, APL 90, 101902 (2007) Dislocation Redirection 415 °C 515 °C 585 °C Claudiu V. Falub, ETH Zürich Unpatterned Patterned Dislocation Management by Surface Facetting 6 December 2012, Brno footer.jpg Assessment of the crystalline quality (HRXRD) 24 16 mm tall Ge towers Continuous Film Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 25 Claudiu V. Falub, ETH Zürich Three Dimensional Nanodiffraction of Ge Crystals X-ray energy 11.07 keV X-ray beam ~ 300´500 nm 6 December 2012, Brno footer.jpg 26 Claudiu V. Falub, ETH Zürich Three Dimensional Nanodiffraction of Ge Crystals 6 December 2012, Brno footer.jpg 27 Claudiu V. Falub, ETH Zürich Nanodiffraction of Isolated Ge Crystals 6 December 2012, Brno footer.jpg 28 Claudiu V. Falub, ETH Zürich Nanodiffraction of Isolated Ge Crystals C:\Users\Claudiu\Documents\Work-ETHZ\Publications\ETHZ\Mojmir\Final figures\NEW\FINAL\Figures\Fig4.png 6 December 2012, Brno footer.jpg 29 Claudiu V. Falub, ETH Zürich C:\Users\Claudiu\Documents\Work-ETHZ\SEM\ESRF-2012\120921 - 8945 ESRF\8945-D1-040.tif C:\Users\Claudiu\Documents\Work-ETHZ\SEM\ESRF-2012\120921 - 8945 ESRF\8945-D1-037.tif C:\Users\Claudiu\Documents\Work-ETHZ\SEM\ESRF-2012\120921 - 8945 ESRF\8945-D1-036.tif 6 December 2012, Brno footer.jpg 30 Strain and Dislocations Free Ge Crystals Claudiu V. Falub, ETH Zürich TUNABLE QUASIPERFECT MATERIALS ! · Unique in the last 40 years of epitaxial work ! · Until recently considered to be impossible ! 6 December 2012, Brno footer.jpg 31 Terracotta Army (China), 3rd century BC Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 32 Claudiu V. Falub, ETH Zürich 26 July 2002 (Biology) 11 October 2002 (Chemistry) 5 September 2008 (Biology) 16 March 2012 (Physics / Materials Science) 4 ETHZ Science covers (1880-2012) 6 December 2012, Brno footer.jpg 33 Claudiu V. Falub, ETH Zürich 16 March 2012 12 August 2011 6 December 2012, Brno footer.jpg 34 Claudiu V. Falub, ETH Zürich International Reactions 6 December 2012, Brno footer.jpg 35 Electrical Measurements SiO2 A n-Si Ge Ge Ge p-Ge p-Si Id Vd tungsten tip ~3 mm Ge §Rectifying behavior with low DC (1 mA/cm2) §Surface leakage doesn’t seem to play a role Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 36 Claudiu V. Falub, ETH Zürich Electrical Measurements V I Id Ip Rp Rs Id , Is diode and saturation currents; b = e/kT , Rs series resistance Rp = 1/Gp (Gp parallel conductance); n – ideality factor Ip shunt curent, Is, n, Rs, Gp ¹ f(V) * J.H. Werner, Appl. Phys. A 47, 291 (1988) 6 December 2012, Brno footer.jpg 37 From Ge crystals to NEXRAY xensors DEVICE PROCESSING (in progress) §8” CMOS wafer §Thinned down to 100 mm §Patterned (DRIE) §Pillars passivation §50 mm Ge towers (backside) §Sealing of the Ge towers §Ge etching §Electrode deposition §Dicing § C:\Users\Claudiu\Desktop\wafer.png C:\Users\Claudiu\Desktop\ISTDM\pics optical microscope\chip.tif Landshut Silicon Foundry GmbH eth_ologo CSEM-regular L-NESS-Logo création graphique Claudiu V. Falub, ETH Zürich 6 December 2012, Brno footer.jpg 38 OUTLOOK Si · III-V, II-VI integration with CMOS · High-efficiency solar cells · Power electronic devices (SiC on Si) · Emitters, resonators, etc. Claudiu V. Falub, ETH Zürich Dislocation And Nerve Damage 6 December 2012, Brno footer.jpg 39 OUTLOOK Claudiu V. Falub, ETH Zürich Integration of III-V optoelectronic devices on Si substrates Si · Small mass · Good thermal conductivity · Large wafer diameter · Mainstream Technology - GaAs · direct band gap alignment · high carrier mobility · Optimum for the development of optoelectro-nic devices · 4% lattice mismatch · 60% thermal mismatch · Anti Phase Domains (APD) CHALLENGES 6 December 2012, Brno http://upload.wikimedia.org/wikipedia/commons/2/2e/Antiphase_domain.JPG Formation of APD GaAs unit cell Ga As footer.jpg 40 OUTLOOK Claudiu V. Falub, ETH Zürich Integration of III-V optoelectronic devices on Si substrates Si · Small mass · Good thermal conductivity · Large wafer diameter · Mainstream Technology - GaAs · direct band gap alignment · high carrier mobility · Optimum for the development of optoelectro-nic devices · 4% lattice mismatch · 60% thermal mismatch · Anti Phase Domains CHALLENGES GaAs Ge/Si In collaboration with 6 December 2012, Brno footer.jpg 41 OUTLOOK Claudiu V. Falub, ETH Zürich Integration of SiGe MQW C:\Users\Claudiu\Documents\Work-ETHZ\SEM\8832\8832-D1-03.tif Si0.1Ge0.9 Si0.1Ge0.9 50´ (21 nm Si0.1Ge0.9 + 10 nm Ge) PATTERNED UNPATTERNED 6 December 2012, Brno footer.jpg 42 SUMMARY Claudiu V. Falub, ETH Zürich ·3D Heteroepitaxial growth of lattice and thermally mismatched semicon-ductor systems on clean, patterned substrate surfaces: §allows dislocation management; §avoids wafer bending; §avoids layer cracks. ·Applicable to wide range of layer thicknesses. ·Diode characteristics (i.e. low DC). §Monolithically integrated X-ray det-ector (high resolution & sensitivity). ·Applicable to other systems (III-V, etc). ·Allows novel applications & devices (e.g. emitters, resonators, etc.) BREAKTHROUGH ! 6 December 2012, Brno footer.jpg 43 http://www.nanotera.ch/images/mainlogo.gif http://www.cosy-net.eu/Images/ESRF%20Logo.jpg eth_ologo CSEM-regular L-NESS-Logo Claudiu V. Falub, ETH Zürich ACKNOWLEDGMENTS 6 December 2012, Brno footer.jpg C:\Users\Claudiu\Pictures\Nepal\15.jpg 44 CAS-2012, Sinaia Claudiu V. Falub, ETH Zürich Thank you for your attention ! Khumjung, Himalaya, Nepal, November 2003