2000 Fiscal Year Final Research Report Summary
Studies of high-temperature point defects and development of crystal growth method free of secondary defects in Si with the use of hydrogen
| Project/Area Number |
11450001
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B).
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Applied materials science/Crystal engineering
|
|---|
| Research Institution | TOHOKU UNIVERSITY |
|---|
Principal Investigator |
SUEZAWA Masashi TOHOKU Univ., Insti. MATERIAS RESEARCH, Prof., 金属材料研究所, 教授 (00005919)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
FUKATA Naoki TOHOKU Univ., Insti.MATERIAS RESEARCH, Assis.Prof., 金属材料研究所, 助手 (90302207)
|
|---|
| Project Period (FY) |
1999 – 2000
|
| Keywords | silicon / vacancy / self-interstitial / hydrogen / oxygen-vacancy pair / complex / optical absorption / electron-irradiation |
|---|
| Research Abstract |
We measured optical absorption spectra after 3-MeV electron-irradiation of hydrogenated Czochralskigrown Si crystals (abbreviated Cz.Si hereafter) at Rt. We observed optical absorption peaks due to various complexes of point defects and impurities. We first describe the result of vacancy-oxygen (VO) pair. The concentration of VO pair was proportional to the 3/4 power of electron dose, contrary to our intuition, i.e., 1. We have not yet succeeded to explain it. The pair formation rate was proportional to the 1/5 power of oxygen concentration. This weak dependence is explained by long diffusion distance of vacancy before captured by oxygen, which is due to high diffusion rate of vacancy and weak interaction between oxygen and vacancy. Contrary to the case of floating-zone grown Si crystals (FZ.Si), vacancyhydrogen complexes were not generated. This is due to VO pair formation because of high concentration of oxygen (about two orders of magnitude larger than that of hydrogen) in Cz.Si. Concentrations of self-interstitial-hydrogen complexes were larger in Cz.Si than in FZ.Si. This is due to lower rate of pair annihilation of vacancy and self-interstitial because vacancies in Cz.Si quickly form pairs with oxygen. We identified defects responsible for peaks at 1870 and 2072 cm^<-1> to be I_2H_2 and V_2H_2, respectively, based on the dendences of peak intensities on dopants and irradiation dose.
We also studied the thermal stability of complexes. VO pairs decreased above 100℃ and, simultaneously, two new peaks at 2126 and 2152 cm^<-1> appeared. These two peaks are due to VOH_2 complex since 2122 and 2145 cm^<-1> peaks are due to VH_2 complex.
|
