Laser fabrication of single crystal architecture (SCAG) in glass: A new frontier of crystal growth

Transcription

1 Laser fabrication of single crystal architecture (SCAG) in glass: A new frontier of crystal growth Himanshu Jain 1, Volkmar Dierolf 2, Dmytro Savytskii 1, Adam Stone 1, Masaaki Sakakura 3, Yasuhiko Shimotsuma 4, Kiyotaka Miura 4, Kazuyuki Hirao 4 1 Dept. of Materials Science and Engineering, 5 E. Packer Ave., Lehigh University, Bethlehem, PA 18015, USA. 2 Department of Physics, Lehigh University, Bethlehem, PA 18015, USA. 3 Office of Society-Academia Collaboration for Innovation, Kyoto University, Kyoto , Japan. 4 Department of Material Chemistry, Kyoto University, T. Komatsu, T. Honma, Y. Benino Nagaoka University, Japan J. Lapointe, R. Kashyap Eng Phys/EE, Ecole Polytechnique de Montreal, Canada N. Tamura Advanced Light Source, LBNL, Berkeley US National Science Foundation (DMR and ). Basic Energy Sciences Div. of Dept. Energy (DE-SC ). International travel support is provided by NSF s IMI-NFG (DMR ). 1 Crystallization, Nagaoka, Oct 13, 2015

2 Outline So what s the challenge with SCAG? Shaping of the frontier a. A functional, working SCAG waveguide b. A novel mode of crystal growth c. Concept of lattice engineering Message: SCAG a new frontier of crystal growth Increasing time to put in practice 2 Crystallization, Nagaoka, Oct 13, 2015

3 Classic method of single crystal growth Si from melt 3 Crystallization, Nagaoka, Oct 13, 2015

4 Convert glass into a ferroelectric single crystal Oxide Model System: LaBGeO 5 Borrelli et al. + Komatsu et al. + ~10 years Lehigh Also, Fujiwara et al., Poumellec et al., Qiu et al., Martin and Kathleen Richardson,.. 1. CW Laser Crystallization: Principle 2La 2 O 3. 2B 2 O 3. 4GeO 2 Sm 2 O 3. La 2 O 3. 2B 2 O 3. 4GeO 2 Sm 3+ Non-radiative transitions absorbed by glass matrix 1064nm laser Ground State 5 San-CAS Sao Carlos March

5 Laser fabrication of single crystal from glass In fs, the absorption is a nonlinear process : Wavelength: 800nm Repetition Rate: 250kHz Pulse Duration: fs Objective NA: 0.55 Temp: 500 C LaBGeO 5 6 Crystallization, Nagaoka, Oct 13, 2015

6 Challenges No crystal formation Too high laser speed Heat damage and cracking Stopped growth - very high degree bend Polycrystalline line- Many seed crystals 7 7 San-CAS Sao Carlos March 26 12

7 Laser Crystallization Seed crystal : Polycrystalline spot A growing single crystal 20 mm 8

8 Ferroelectric single crystal architecture - near the surface in LaBGeO 5 Polarized picture SHG picture 9 San-CAS Sao Carlos March 26 12

9 Orientation analysis: Diffraction patterns Elemental analysis: EDS line scan La Sm Ge Line is, Crystalline Single crystal Same composition as glass 10

10 Crystal growth vs. fs laser scan rate (without aberration correction) The caterpillar seems to have wings, which decrease with increasing scanning rate. 11Crystallization, Nagaoka, Oct 13, 2015

11 Heat Gradient and Focal Depth Laser heating creates refractive index modification Boundary is determined by heat gradient shape Heat gradient and crystal growth will vary with focal depth

12 3D single crystal line Birefringence maps indicate uniformity of orientation, shape and size Uniformity varies from line to line even after aberration correction Top: birefringence maps show orientation and thickness variation Bottom: optical micrographs show corresponding cross-sections The first indefinitely long 3D SCAG waveguide is made with loss 2.64 db/cm. It is also active FE! Stone et al. Sci. Rep. 5 (2015)

13 Fs: Beginning of glass crystal transformation Defects (black arrow) precede xtal (white arrow), but via an intermediate phase (white dashed arrow) Even in the interior, nucleation is heterogeneous Poumellec, et al. Liu, Zeng, Brisset, Chen, Zhao, Lancry 14Crystallization, Nagaoka, Oct 13, 2015

14 Erbium Fluorescence as Mapped by CEES 1% Er Glass 1% Er Furnace Crystallized 1% Er Laser Crystallized Erbium is incorporated into LaBGeO 5, at the La site. Peaks are broadened and some exhibit fluorescence line narrowing, indicating significant strain due to confinement or non-optimal growth conditions.

15 A conceptual model: Key factors (i) Intrinsic growth rate anisotropy of the given crystal. It controls growth rate as a function of lattice orientation relative to melt interface. (ii) The temperature dependence of growth rate, which usually shows a peak (at Tx). Its profile is crucial since fs laser crystallization is highly non-isothermal with a very steep temperature gradient. (iii) Direction of laser scanning, which provides directional selectivity among nuclei competing for the growth space. 17 San-CAS Sao Carlos March 26 12

16 Next level of challenges: incongruently melting, unstable or metastable materials: ChG US Nat l Res. Council, Frontiers in Crystalline Matter: From Discovery to Technology (2009). Full potential of emerging materials is limited by the lack of methods for growing single crystals of these oftentimes incongruently melting, unstable or metastable materials. Sb 2 S 3 1. Photoexpansion 2. Selective evaporation/ decomposition 3. Oxidation Selective evaporation Photoexpansion Oxidation 18Crystallization, Nagaoka, Oct 13, 2015

17 Single crystal architecture on Sb 2 S 3 glass Image of EBSD scanned area, 70 0 EBSD, tilt compensated Image quality map Inverse pole figure map with orientations of Sb 2 S 3 lattice cell, normal direction 21Crystallization, Nagaoka, Oct 13, 2015

18 Message It is possible to write 1D, 2D and 3D SCAG in glass. The first functional single crystal waveguide deep inside a glass is demonstrated. New active optical devices will emerge in near future. Single crystal fabrication by solid-solid transformation of glass is shown unequivocally, opening the possibility of fabricating single crystals of materials that melt incongruently, decompose or undergo phase transformation on heating to melt temperature. The discovery of single crystal growth with rotating lattice opens the possibility to engineer the lattice of SCAG. The field of SCAG, which started right here in Nagaoka is now a new frontier of single crystal growth 22Crystallization, Nagaoka, Oct 13, 2015