Fermi-Level Unpinning Technique with Excellent Thermal Stability. for n-Type Germanium
- Authors
- Kim, Gwang-Sik; Kim, Seung-Hwan; Lee, Tae In; Cho, Byung Jin; Choi, Changhwan; Shin, Changhwan; Shim, Joon Hyung; Kim, Jiyoung; Yu, Hyun-Yong
- Issue Date
- 18-10월-2017
- Publisher
- AMER CHEMICAL SOC
- Keywords
- germanium; metal-interlayer-semiconductor structure; thermal stability; Schottky barrier height; tantalum nitride; aluminum-doped zinc oxide
- Citation
- ACS APPLIED MATERIALS & INTERFACES, v.9, no.41, pp.35988 - 35997
- Indexed
- SCIE
SCOPUS
- Journal Title
- ACS APPLIED MATERIALS & INTERFACES
- Volume
- 9
- Number
- 41
- Start Page
- 35988
- End Page
- 35997
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/81888
- DOI
- 10.1021/acsami.7b10346
- ISSN
- 1944-8244
- Abstract
- A metal interlayer semiconductor (M I S) structure with excellent thermal stability and electrical performance for a nonalloyed contact scheme is developed, and considerations for designing thermally stable M I S structure are demonstrated on the basis of n-type germanium (Ge). A thermal annealing process makes M-I-S structures lose their Fermi-level unpinning and electron Schottky barrier height reduction effect in two mechanisms: (1) oxygen (O) diffusion from the interlayer to the contact metal due to high reactivity of a pure metal contact with O and (2) interdiffusion between the contact metal and semiconductor through grain boundaries of the interlayer. A pure metal contact such as titanium (Ti) provides very poor thermal stability due to its high reactivity with O. A structure with a tantalum nitride (TaN) metal contact and a titanium dioxide (TiO2) interlayer exhibits moderate thermal stability up to 400 degrees C because TaN has much lower reactivity with O than with Ti. However, the TiO2 interlayer cannot prevent the interdiffusion process because it is easily crystallized during thermal annealing and its grain boundaries act as diffusion path. A zinc oxide (ZnO) interlayer doped with group-III elements, such as an aluminum-doped ZnO (AZO) interlayer, acts as a good diffusion barrier due to its high crystallization temperature. A TaN/AZO/n-Ge structure provides excellent thermal stability above 500 degrees C as it can prevent both O diffusion and interdiffusion processes; hence, it exhibits Ohmic contact properties for all thermal annealing temperatures. This work shows that, to fabricate a thermally stable and low resistive M-I-S contact structure, the metal contact should have low reactivity with O and a low work function, and the interlayer should have a high crystallization temperature and a low conduction band offset to Ge. Furthermore, new insights are provided for designing thermally stable M I S contact schemes for any semiconductor material that suffers from the Fermi-level pinning problem.
- Files in This Item
- There are no files associated with this item.
- Appears in
Collections - College of Engineering > Department of Mechanical Engineering > 1. Journal Articles
- College of Engineering > School of Electrical Engineering > 1. Journal Articles
Items in ScholarWorks are protected by copyright, with all rights reserved, unless otherwise indicated.