세미나안내

[2014 01 10] 특별세미나

Understanding of point defects in oxides and their impact on electronic devices from first principles

MSE Graduate Students and Researchers

관리자 | 2014.01.10 11:30 | 조회 2883


Reception: MSE Graduate Students and Researchers

Reference: MSE Professors

Subject: MSE Special Seminar_ Dr. Minseok Choi

 

 Date: 2014. 1. 10(FRI), 16:00 ~ 17:00

 Place: Science Building, Room. 202 Multimedia Room

 Title: Understanding of point defects in oxides and their impact on electronic devices from first principles

 Speaker: Dr. Minseok Choi

Advanced Characterization and Analysis Group, Korea Institute of Materials Science (KIMS)

 Host of a Seminar: Prof. Junwoo Son

 

 Abstract

Using first-principles calculations based on density-functional theory, point defects in the structural, electrical, and optical properties of oxides have been studied. In this talk, our recent results for native donors in SrTiO3 will be presented. For SrTiO3, the issue of what cause the fascinating physical such as very high n-type conductivity, visible-light emission, and ferroelectricity without doping is still under debate. These properties have typically been attributed to the O vacancy or its complexes, but the role of these defects has not been well explored. Our calculations show that the off-centered Ti antisite is likely to form, even comparable with O vacancy, and introduces deep, localized states in the gap. Based on these results, we conclude that the experimentally observed properties could be related to the Ti antisite. We find that the O vacancy induces local octahedral rotation even in the cubic phase, with the electron localization near the vacancy. Such electronic structure provides an explanation for the n-type conductivity in reduced SrTiO3 and for the visible-light emission as well as the Ti antisite. We have also examined how point defects in gate dielectrics impact on the performance of metal-oxide-semiconductor (MOS) devices.  High-k oxides are intensively studied for industrial applications, such as alternative gate dielectrics in MOS devices. Promising results have been achieved with Al2O3/III-V and HfO2/Si MOS structures, which exhibit relatively low densities of interface states. However, the presence of carrier traps and fixed charges near the oxide/semiconductor interface still poses serious limitations in device performance. We investigate the effects of impurities in Al2O3 and HfO2, which could be introduced during the deposition process. By analyzing the position of the impurity levels with respect to the semiconductor band edges, the role of the impurities in the electrical properties of MOS devices is addressed. Our results show that the C impurity can act as carrier traps and/or lead to leakage current through the gate dielectric. N impurity is a likely source of fixed charge, but may be effective in alleviating the problem of carrier traps and fixed charges associated with native defects.

 

Department of Materials Science and Engineering



177개(8/9페이지)
세미나안내
번호 제목 글쓴이 조회 날짜
37 [2014 05 07] 정기세미나 8th 관리자 2197 2014.05.07 10:25
36 [2014 05 03] 특별세미나 (BK21PLUS-고분자연구소) 관리자 2507 2014.04.30 11:34
35 [2014 04 30] 정기세미나 7th 관리자 2494 2014.04.29 11:42
34 [2014 04 24] 특별세미나 (BK21PLUS-IBS) 첨부파일 관리자 2529 2014.04.16 14:19
33 [2014 04 16] 정기세미나 6th 관리자 2357 2014.04.14 13:59
32 [2014 04 15] 특별세미나 (신소재공학과 석학교수) 관리자 2866 2014.04.14 13:07
31 [2014 04 09] 정기세미나 5th 관리자 2508 2014.04.01 08:58
30 [2014 04 17] 특별세미나 (BK21PLUS) 관리자 2632 2014.04.02 11:30
29 [2014 04 02] 정기세미나 4th 관리자 2630 2014.04.01 08:58
28 [2014 03 26] 정기세미나 3rd 관리자 2970 2014.03.25 09:07
27 [2014 03 28] 특별세미나 (BK21PLUS) 관리자 2414 2014.03.24 15:43
26 [2014 03 20] 특별세미나 (BK21PLUS) 관리자 2735 2014.03.17 13:09
25 [2014 03 19] 정기세미나 2nd 관리자 2382 2014.03.17 13:08
24 [2014 03 12] 정기세미나 1st 관리자 2587 2014.03.17 13:07
23 [2014 03 05] 정기특별세미나 관리자 2525 2014.03.03 11:21
22 [2014 03 06] 특별세미나 (BK21PLUS) 관리자 2633 2014.03.03 11:19
21 [2014 02 25] KIST Showcase 안내 첨부파일 관리자 2756 2014.02.10 10:53
20 [2014 01 27] IBS 초청 세미나 첨부파일 관리자 3169 2014.01.24 16:52
19 [2014 01 23] IBS 초청 세미나 첨부파일 관리자 3242 2014.01.15 15:36
18 [2014 01 14] 특별세미나 (BK21PLUS) 관리자 2909 2014.01.13 09:28