{"title":"氢在硅表面的扩散","authors":"M. Dürr , U. Höfer","doi":"10.1016/j.progsurf.2013.01.001","DOIUrl":null,"url":null,"abstract":"<div><p>Diffusion of atomic hydrogen on silicon serves as a model system for the investigation of thermally activated diffusion processes of covalently bound adsorbates on semiconductor surfaces. Over the past two decades, a detailed understanding of the hopping mechanisms for H/Si(0<!--> <!-->0<!--> <!-->1) and H/Si(1<!--> <!-->1<!--> <!-->1) has been obtained using a variety of experimental and theoretical methods. Hydrogen diffusion on silicon is in general characterized by energy barriers that are substantially larger than for adsorbate diffusion on metal surfaces, by the occurrence of different pathways on one surface, as well as by a strong participation of the underlying lattice in the hopping process.</p><p>In the case of the flat Si(0<!--> <!-->0<!--> <!-->1) surface, three diffusion pathways were identified: site exchange within one Si dimer, hopping along dimer rows, and hopping across dimer rows, with barriers of 1.4, 1.7 and 2.4<!--> <!-->eV, respectively. These barriers correlate with the distances of the involved adsorption sites of 2.4, 3.8 and 5.2<!--> <!-->Å. While hydrogen diffusion on Si(0<!--> <!-->0<!--> <!-->1) is strongly anisotropic at surface temperatures below 700<!--> <!-->K, the measurement of high hopping rates by means of a combination of pulsed laser heating and scanning tunneling microscopy reveals similar jump frequencies around 10<sup>8</sup> <!-->s<sup>−1</sup> at 1400<!--> <!-->K. Diffusion across steps is found to occur with similar speed as diffusion along dimer rows.</p><p>Hydrogen diffusion on Si(1<!--> <!-->1<!--> <!-->1) 7<!--> <!-->×<!--> <!-->7 involves 4.4-Å-long jumps between restatom and adatom sites, accompanied by strong distortions of the adatom backbonds. Crossing the unit-cell boundaries via a 6.7-Å-long migration pathway between two adatoms is the rate limiting process for diffusion on macroscopic length scales, which has an activation energy of 1.5<!--> <!-->eV.</p></div>","PeriodicalId":416,"journal":{"name":"Progress in Surface Science","volume":null,"pages":null},"PeriodicalIF":8.7000,"publicationDate":"2013-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.progsurf.2013.01.001","citationCount":"40","resultStr":"{\"title\":\"Hydrogen diffusion on silicon surfaces\",\"authors\":\"M. Dürr , U. Höfer\",\"doi\":\"10.1016/j.progsurf.2013.01.001\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Diffusion of atomic hydrogen on silicon serves as a model system for the investigation of thermally activated diffusion processes of covalently bound adsorbates on semiconductor surfaces. Over the past two decades, a detailed understanding of the hopping mechanisms for H/Si(0<!--> <!-->0<!--> <!-->1) and H/Si(1<!--> <!-->1<!--> <!-->1) has been obtained using a variety of experimental and theoretical methods. Hydrogen diffusion on silicon is in general characterized by energy barriers that are substantially larger than for adsorbate diffusion on metal surfaces, by the occurrence of different pathways on one surface, as well as by a strong participation of the underlying lattice in the hopping process.</p><p>In the case of the flat Si(0<!--> <!-->0<!--> <!-->1) surface, three diffusion pathways were identified: site exchange within one Si dimer, hopping along dimer rows, and hopping across dimer rows, with barriers of 1.4, 1.7 and 2.4<!--> <!-->eV, respectively. These barriers correlate with the distances of the involved adsorption sites of 2.4, 3.8 and 5.2<!--> <!-->Å. While hydrogen diffusion on Si(0<!--> <!-->0<!--> <!-->1) is strongly anisotropic at surface temperatures below 700<!--> <!-->K, the measurement of high hopping rates by means of a combination of pulsed laser heating and scanning tunneling microscopy reveals similar jump frequencies around 10<sup>8</sup> <!-->s<sup>−1</sup> at 1400<!--> <!-->K. Diffusion across steps is found to occur with similar speed as diffusion along dimer rows.</p><p>Hydrogen diffusion on Si(1<!--> <!-->1<!--> <!-->1) 7<!--> <!-->×<!--> <!-->7 involves 4.4-Å-long jumps between restatom and adatom sites, accompanied by strong distortions of the adatom backbonds. Crossing the unit-cell boundaries via a 6.7-Å-long migration pathway between two adatoms is the rate limiting process for diffusion on macroscopic length scales, which has an activation energy of 1.5<!--> <!-->eV.</p></div>\",\"PeriodicalId\":416,\"journal\":{\"name\":\"Progress in Surface Science\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":8.7000,\"publicationDate\":\"2013-02-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://sci-hub-pdf.com/10.1016/j.progsurf.2013.01.001\",\"citationCount\":\"40\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Progress in Surface Science\",\"FirstCategoryId\":\"5\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0079681613000026\",\"RegionNum\":2,\"RegionCategory\":\"工程技术\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"CHEMISTRY, PHYSICAL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Progress in Surface Science","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0079681613000026","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
Diffusion of atomic hydrogen on silicon serves as a model system for the investigation of thermally activated diffusion processes of covalently bound adsorbates on semiconductor surfaces. Over the past two decades, a detailed understanding of the hopping mechanisms for H/Si(0 0 1) and H/Si(1 1 1) has been obtained using a variety of experimental and theoretical methods. Hydrogen diffusion on silicon is in general characterized by energy barriers that are substantially larger than for adsorbate diffusion on metal surfaces, by the occurrence of different pathways on one surface, as well as by a strong participation of the underlying lattice in the hopping process.
In the case of the flat Si(0 0 1) surface, three diffusion pathways were identified: site exchange within one Si dimer, hopping along dimer rows, and hopping across dimer rows, with barriers of 1.4, 1.7 and 2.4 eV, respectively. These barriers correlate with the distances of the involved adsorption sites of 2.4, 3.8 and 5.2 Å. While hydrogen diffusion on Si(0 0 1) is strongly anisotropic at surface temperatures below 700 K, the measurement of high hopping rates by means of a combination of pulsed laser heating and scanning tunneling microscopy reveals similar jump frequencies around 108 s−1 at 1400 K. Diffusion across steps is found to occur with similar speed as diffusion along dimer rows.
Hydrogen diffusion on Si(1 1 1) 7 × 7 involves 4.4-Å-long jumps between restatom and adatom sites, accompanied by strong distortions of the adatom backbonds. Crossing the unit-cell boundaries via a 6.7-Å-long migration pathway between two adatoms is the rate limiting process for diffusion on macroscopic length scales, which has an activation energy of 1.5 eV.
期刊介绍:
Progress in Surface Science publishes progress reports and review articles by invited authors of international stature. The papers are aimed at surface scientists and cover various aspects of surface science. Papers in the new section Progress Highlights, are more concise and general at the same time, and are aimed at all scientists. Because of the transdisciplinary nature of surface science, topics are chosen for their timeliness from across the wide spectrum of scientific and engineering subjects. The journal strives to promote the exchange of ideas between surface scientists in the various areas. Authors are encouraged to write articles that are of relevance and interest to both established surface scientists and newcomers in the field.