New! Sign up for our free email newsletter.
Science News
from research organizations

Viewing atomic structures of dopant atoms in 3-D relating to electrical activity in a semiconductor

Date:
December 27, 2017
Source:
Tokyo Institute of Technology
Summary:
Scientists have just developed a novel approach to determine and visualize the three-dimensional (3-D) structure of individual dopant atoms using SPring-8.
Share:
FULL STORY

Scientists at Tokyo Institute of Technology (Tokyo Tech) and their research team involving researchers of JASRI, Osaka University, Nagoya Institute of Technology, and Nara Institute of Science and Technology have just developed a novel approach to determine and visualize the three-dimensional (3D) structure of individual dopant atoms using SPring-8. The technique will help improve the current understanding of the atomic structures of dopants in semiconductors correlated with their electrical activity and thus help support the development of new manufacturing processes for high-performance devices.

Using a combination of spectro-photoelectron holography, electrical property measurements, and first-principles dynamics simulations, the 3D atomic structures of dopant impurities in a semiconductor crystal were successfully revealed. The need for a better understanding of the atomic structures of dopants in semiconductors had been long felt, mainly because the current limitations on active dopant concentrations result from the deactivation of excess dopant atoms by the formation of various types of clusters and other defect structures.

The search for techniques to electrically activate the dopant impurities in semiconductors with high efficiency and/or at high concentrations have always been an essential aspect of semiconductor device technology. However, despite various successful developments, the achievable maximum concentration of active dopants remains limited. Given the impact of the dopant atomic structures in this process, these structures had been previously investigated using both theoretical and experimental approaches. However, direct observation of the 3D structures of the dopant atomic arrangements had hitherto been difficult to achieve.

In this study, Kazuo Tsutsui at Tokyo Tech and colleagues involving researchers at JASRI, Osaka University, Nagoya Institute of Technology, and Nara Institute of Science and Technology developed spectro-photoelectron holography using SPring-8, and leveraged the capabilities of photoelectron holography in determining the concentrations of dopants at different sites, based on the peak intensities of the photoelectron spectrum, and classified electrically active / inactive atomic sites. These structures directly related with the density of carriers. In this approach, soft X-ray excitation of the core level electrons leads to the emission of photoelectrons from various atoms, whose waves are then scattered by the surrounding atoms. The resulting interference pattern creates the photoelectron hologram, which may then be captured with an electron analyzer. The photoelectron spectra acquired in this manner contain information from more than one atomic site. Therefore, peak fitting is performed to obtain the photoelectron hologram of individual atomic sites. The combination of this technique with first-principles simulations allows the successful estimation of the 3D structure of the dopant atoms, and the assessment of their different chemical bonding states. The method was used to estimate the 3D structures of arsenic atoms doped onto a silicon surface. The obtained results fully demonstrated the power of the proposed method and allowed confirmation of several previous results.

This work demonstrates the potential of spectro-photoelectron holography for the analysis of impurities in semiconductors. This technique allows analyses that are difficult to perform with conventional approaches and should therefore be useful in the development of improved doping techniques and, ultimately, in supporting the manufacture of high-performance devices.

SPring-8

The name "SPring-8" comes from "Super Photon ring-8 GeV." It is owned by RIKEN and located in Harima Science Garden City, Hyogo Prefecture, Japan. SPring-8 generates the world's highest-performance synchrotron radiation and was opened in 1997 to users from universities, research institutes, and companies. Synchrotron radiation is an electromagnetic wave that is produced when electron beams, accelerated to nearly the speed of light, are bent in a high magnetic field. High-intensity synchrotron radiation in a wide range of energy from infrared to soft and hard X-ray regions is available at SPring-8.


Story Source:

Materials provided by Tokyo Institute of Technology. Note: Content may be edited for style and length.


Journal Reference:

  1. Kazuo Tsutsui, Tomohiro Matsushita, Kotaro Natori, Takayuki Muro, Yoshitada Morikawa, Takuya Hoshii, Kuniyuki Kakushima, Hitoshi Wakabayashi, Kouichi Hayashi, Fumihiko Matsui, Toyohiko Kinoshita. Individual Atomic Imaging of Multiple Dopant Sites in As-Doped Si Using Spectro-Photoelectron Holography. Nano Letters, 2017; 17 (12): 7533 DOI: 10.1021/acs.nanolett.7b03467

Cite This Page:

Tokyo Institute of Technology. "Viewing atomic structures of dopant atoms in 3-D relating to electrical activity in a semiconductor." ScienceDaily. ScienceDaily, 27 December 2017. <www.sciencedaily.com/releases/2017/12/171227145938.htm>.
Tokyo Institute of Technology. (2017, December 27). Viewing atomic structures of dopant atoms in 3-D relating to electrical activity in a semiconductor. ScienceDaily. Retrieved March 28, 2024 from www.sciencedaily.com/releases/2017/12/171227145938.htm
Tokyo Institute of Technology. "Viewing atomic structures of dopant atoms in 3-D relating to electrical activity in a semiconductor." ScienceDaily. www.sciencedaily.com/releases/2017/12/171227145938.htm (accessed March 28, 2024).

Explore More

from ScienceDaily

RELATED STORIES