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Surface potential response along GaP nanowires synthesized with a mixed phases.
- 1. Surface potential response from GaP nanowires synthesized with mixed crystal phases B Kyeyune1,2 , E Soboleva1 , P Geydt3 , V Khayrudinov4 , P Alekseev5 , H Lipsanen4 and E L˚ahderanta1 2 Universit¨at Osnabr¨uck, Barbarastraße, Germany. 3 Novosibirsk State University, Russia. 4 Aalto University, Finland 5 Laboratory of Surface Optics, Ioffe Surface potential response from GaP nanowires synthesized with mixed crystal phases B Kyeyune1,2, E Soboleva1, P Geydt3, V Khayrudinov4, P Alekseev5, H Lipsanen4 and E L˚ahderanta1 2 Universit¨at Osnabr¨uck, Barbarastraße, Germany. 3 Novosibirsk State University, Russia. 4 Aalto University, Finland 5 Laboratory of Surface Optics, Ioffe Institute, Russia International conference PhysicA.SPb/2019
- 2. Surface potential response from GaP nanowires synthesized with mixed crystal phases B Kyeyune1,2 , E Soboleva1 , P Geydt3 , V Khayrudinov4 , P Alekseev5 , H Lipsanen4 and E L˚ahderanta1 2 Universit¨at Osnabr¨uck, Barbarastraße, Germany. 3 Novosibirsk State University, Russia. 4 Aalto University, Finland 5 Laboratory of Surface Optics, Ioffe Outline Semiconductor nanowires (NWs). Influence of crystal structure of semiconductor NWs. Kelvin probe force microscopy (KPFM). Experimental results. Conclusion.
- 3. Surface potential response from GaP nanowires synthesized with mixed crystal phases B Kyeyune1,2 , E Soboleva1 , P Geydt3 , V Khayrudinov4 , P Alekseev5 , H Lipsanen4 and E L˚ahderanta1 2 Universit¨at Osnabr¨uck, Barbarastraße, Germany. 3 Novosibirsk State University, Russia. 4 Aalto University, Finland 5 Laboratory of Surface Optics, Ioffe Semiconductor NWs (a) SEM Image of GaP NWs (b) VLS Growth mechanism Key Features: High aspect ratio. High surface area. Quantum confinement. Controlled crystal growth.
- 4. Surface potential response from GaP nanowires synthesized with mixed crystal phases B Kyeyune1,2 , E Soboleva1 , P Geydt3 , V Khayrudinov4 , P Alekseev5 , H Lipsanen4 and E L˚ahderanta1 2 Universit¨at Osnabr¨uck, Barbarastraße, Germany. 3 Novosibirsk State University, Russia. 4 Aalto University, Finland 5 Laboratory of Surface Optics, Ioffe What is our concern? response of surface potential to mixed phases in GaP NWs. Figure: ZincBlende (ZB) Figure: Wurtzite (WZ)
- 5. Surface potential response from GaP nanowires synthesized with mixed crystal phases B Kyeyune1,2 , E Soboleva1 , P Geydt3 , V Khayrudinov4 , P Alekseev5 , H Lipsanen4 and E L˚ahderanta1 2 Universit¨at Osnabr¨uck, Barbarastraße, Germany. 3 Novosibirsk State University, Russia. 4 Aalto University, Finland 5 Laboratory of Surface Optics, Ioffe Influence of crystal structure of semiconductor NWs. (a) Assali S et al 2013 [1] (b) Dunaevskiy M et al 2017 [2] GaP NW with the ZB crystal structure has an indirect band gap and otherwise for WZ crystal structure. InP NW have higher young’s modulus for WZ structures than ZB structures.
- 6. Surface potential response from GaP nanowires synthesized with mixed crystal phases B Kyeyune1,2 , E Soboleva1 , P Geydt3 , V Khayrudinov4 , P Alekseev5 , H Lipsanen4 and E L˚ahderanta1 2 Universit¨at Osnabr¨uck, Barbarastraße, Germany. 3 Novosibirsk State University, Russia. 4 Aalto University, Finland 5 Laboratory of Surface Optics, Ioffe Kelvin probe force microscopy (KPFM) (a) Kelvin Technique (b) FM-KPFM schematic Lift mode (lift height 50 nm). In FM-KPFM we measure the frequency shift ∆f , ∆f = − f0 2k δFts δz , Fts = − δC(z) δz (UDC ± UCPD) +UAC sinωt f0 ≈ 300 kHz and k ≈ 0.8 N/m
- 7. Surface potential response from GaP nanowires synthesized with mixed crystal phases B Kyeyune1,2 , E Soboleva1 , P Geydt3 , V Khayrudinov4 , P Alekseev5 , H Lipsanen4 and E L˚ahderanta1 2 Universit¨at Osnabr¨uck, Barbarastraße, Germany. 3 Novosibirsk State University, Russia. 4 Aalto University, Finland 5 Laboratory of Surface Optics, Ioffe Experimental Results Figure: a Figure: b Structure A-B (mV) A-D (mV) B-C (mV) C-D (mV) Figure a 62±26 63±22 42±22 44±17 Figure b 65±37 - - - Table: Surface potential results
- 8. Surface potential response from GaP nanowires synthesized with mixed crystal phases B Kyeyune1,2 , E Soboleva1 , P Geydt3 , V Khayrudinov4 , P Alekseev5 , H Lipsanen4 and E L˚ahderanta1 2 Universit¨at Osnabr¨uck, Barbarastraße, Germany. 3 Novosibirsk State University, Russia. 4 Aalto University, Finland 5 Laboratory of Surface Optics, Ioffe Conclusion A single GaP NW with mixed crystal phases along the growth direction was found to have different surface potential values along the surface. With scanning tunnelling electron microscopy (STEM) alongside KPFM one can establish a distinctive difference. UHV measurements would bring us to better accuracy.
- 9. Surface potential response from GaP nanowires synthesized with mixed crystal phases B Kyeyune1,2 , E Soboleva1 , P Geydt3 , V Khayrudinov4 , P Alekseev5 , H Lipsanen4 and E L˚ahderanta1 2 Universit¨at Osnabr¨uck, Barbarastraße, Germany. 3 Novosibirsk State University, Russia. 4 Aalto University, Finland 5 Laboratory of Surface Optics, Ioffe Reference Assali S et al 2013 Direct band gap wurtzite gallium phosphide nanowires Nano letters 13 1559-63. Dunaevskiy M et al 2017 Young’s modulus of wurtzite and zinc blende InP nanowires. Nano letters 17 3441-46.
- 10. Surface potential response from GaP nanowires synthesized with mixed crystal phases B Kyeyune1,2 , E Soboleva1 , P Geydt3 , V Khayrudinov4 , P Alekseev5 , H Lipsanen4 and E L˚ahderanta1 2 Universit¨at Osnabr¨uck, Barbarastraße, Germany. 3 Novosibirsk State University, Russia. 4 Aalto University, Finland 5 Laboratory of Surface Optics, Ioffe