Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2016)
    Thin Films Tuesday Sessions
       Session TF-TuP

Paper TF-TuP22
Improvement of Detection Limit for Hydrogen by High-resolution ERDA

Tuesday, December 13, 2016, 4:00 pm, Room Mauka

Session: Thin Films Poster Session
Presenter: Daiichiro Sekiba, University of Tsukuba, Japan
Authors: D. Sekiba, University of Tsukuba, Japan
I. Harayama, University of Tsukuba, Japan
T. Tamura, University of Tsukuba, Japan
Y. Watahiki, University of Tsukuba, Japan
K. Tsujita, University of Tsukuba, Japan
Correspondent: Click to Email
Recently high-resolution ERDA (Elastic Recoil Detection Analysis) is installed in UTTAC (University of Tsukuba, Tandem Accelerator Complex) in Japan, which consists of a 90 degree magnetic sector lens and a position sensitive detector (PSD). High-resolution ERDA is one of the powerful tools to obtain the depth profile of hydrogen with the depth resolution of sub-nano-meter, while its detection limit for hydrogen has not been good enough to discuss the hydrogen concentration at interfaces made on semiconductor substrates. The main origins of noise, which makes the detection limit worse, are dark current in the micro-channel plate (MCP) used as PSD and stray particles in the vacuum chambers. We found out that the dark current can be distinguished from the desirable signal by a coincidence measurement using two MCPs. The two MCPs detect the recoil of hydrogen ion and secondary electrons from stopper foil, respectively. The dark current noise can be suppressed under the 1% to take the coincidence not only of the detection time but also the positions on the two MCP. The second coincidence can remove the chance coincidence of two dark current signals. We have also tried to develop a new PSD based on solid state detector (SSD) usually made by silicon. In this case the PSD has the energy resolution of detected particle, so that, we can distinguish also the stray particles. We report the recent achievement using these new detectors.