1 / 13

NH 3 on Si(111)7x7

NH 3 on Si(111)7x7. Why NH 3 on Si(111)7x7 ?. Si 3 N 4 ! ! !. Ammonia has been the most frequently used nitrogen source in chemical vapor deposition(CVD) growth.

kiele
Download Presentation

NH 3 on Si(111)7x7

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. NH3 on Si(111)7x7

  2. Why NH3 on Si(111)7x7 ? Si3N4 ! ! ! Ammonia has been the most frequently used nitrogen source in chemical vapor deposition(CVD) growth. The structural quality and the chemical stability of the silicon nitride (Si3N4) films are crucial in various industrial applications like as metal-oxide semiconductor devices. The complex Si(111)7x7 reconstruction, which displays a variety of surface sites, provides the opportunity to study the effect of local electronic structure modification.

  3. Purpose of the study Find out the different adsorption and dissociation pathways of NH3 on the surfaces between Si(100) and Si(111). Discover detail information about site-selective NH3reaction with Si(111)7x7. NH3 -> NH2 + H NH2 -> NH + H Si3N4 ?

  4. 2x1 1x2 Adatom : 12 Restatom : 6 Hole :1 Si(111)7x7 vs. Si(100)2x1 Heating up to 950˚C Heating up to 1470K

  5. Experiments M. Björkqvist et al. Phys. Rev. B 57, 2327 (1998) NH3 on Si(111)7x7: Dissociation and surface reactions The photoemission experiments using beam line 22 at the National Synchrotron Radiation Facility MAX-LAB(Lund, Sweden) Jeong Won Kim, Han Woong Yeom Surf. Sci. Lett. 546 (2003) L820-L828 Thermal decomposition of HN3 on the Si(100) surface The photoemission experiments using X-ray beam line(8A1) connected undulator source at Pohang Accelerator Laboratory(PAL) Myung-Ho Kang et al. Phys. Rev. B 68, 205307 (2003) Theory on the site-selective HN3 reaction with Si(111)-(7x7) Supercomputing Center at POSTECH

  6. N 1s core-level spectra (a) For increasing ammonia exposures at RT (b) After annealing of the 5L dose surface The case of Si(100) surface A1 : NH3 A2 : HN2 A3 : NH A4 : N N1 : N N2 : NH N3 : NH2 1L = 1x10-6 Torrxsec

  7. N 1s core-level spectra NH2≤ 600K 500K ≤ NH ≤ 700K 500K ≤ N Coexistence : 500 ~ 700K NH2≤ 650K 200K ≤ NH ≤ 750K N ≤ 700K Coexistence : 650 ~ 700K

  8. Si 2p core-level spectra (b) After annealing of the 5L dose surface (a) The clean and ammonia reacted surface at RT The case of Si(100) surface 2p1/2 (99.9eV) 2p3/2 (99.3eV) S1 : restaom Si 2p3/2 D : Si 2+ (101.1eV) E : oxidized silicon SS : second layer atoms C : third layer or defect atoms S : updimer atoms

  9. Valence-band spectra (a) For increasing ammonia exposures at RT (b) After annealing of the 5L dose surface V1 : N pπ (4.9eV) V2 : N-H (10.6eV) V3 : Si-H (5.4eV) V4 :N2p,Si3p (7.4eV) S1 : restatom DB (0.9eV) S2 : adatom DB (0.3eV) S3 : adatom backbonds (1.9eV)

  10. DFT (Density functional theory) Infinite slab geometry Solid : A Dash : B Calculated adsorption energy

  11. Summary NH3 on Si(100)2x1 NH2-> NH2 + NH->NH2+ NH + N ->Si3N4 + N NH3 on Si(111)7x7 NH3 + NH2 + NH ->NH2 + NH + N -> NH + N-> N -> SiCx + SiNx + SiOx Adatom : restatom = 2:1 After reaction of NH3 on Si(111)7x7 surface Adatom : restatom = 1:0 Early saturation of Si restatom feature doesn’t prove easily about the site-selectivity!

  12. What I want to know Chemisorption mechanism of NH3 on Si(111)7x7 Under 200K Enlarged valence band of the adatom and restatom part using beam energy level hv = 37(40.1)eV

More Related