Naohisa Inoue

Behavior of nitrogen in Si crystal during irradiation and post-annealing

Radiation induced complexes in nitrogen (N) -doped silicon crystal was investigated by highly sensitive infrared absorption spectroscopy. The absorption by N2 pair was reduced by the electron irradiation in FZ crystals. The absorptions appeared on both sides of N2 line at 766 cm−1, at about 725 and 778 cm−1. By the annealing, N2 lines recovered a little at 600 °C and mostly at 800 °C. The above new absorption lines reduced by the annealing at lower temperatures and other absorption appeared. In CZ silicon, N2 lines did not change by the irradiation. Dominant absorption in low carbon FZ silicon was that of C-rich type complexes, VO and InCiOim(n=0–3, m=0,1). Dominant absorption in the irradiated low carbon CZ silicon was that of C-lean type complexes InO2+mi(n=1, 2, m=0, 1), and the decrease of C-lean type O2i and TDD was observed. By the annealing of CZ Si, VOn (n=2–4) formation and annihilation was observed.Radiation induced complexes in nitrogen (N) -doped silicon crystal was investigated by highly sensitive infrared absorption spectroscopy. The absorption by N2 pair was reduced by the electron irradiation in FZ crystals. The absorptions appeared on both sides of N2 line at 766 cm−1, at about 725 and 778 cm−1. By the annealing, N2 lines recovered a little at 600 °C and mostly at 800 °C. The above new absorption lines reduced by the annealing at lower temperatures and other absorption appeared. In CZ silicon, N2 lines did not change by the irradiation. Dominant absorption in low carbon FZ silicon was that of C-rich type complexes, VO and InCiOim(n=0–3, m=0,1). Dominant absorption in the irradiated low carbon CZ silicon was that of C-lean type complexes InO2+mi(n=1, 2, m=0, 1), and the decrease of C-lean type O2i and TDD was observed. By the annealing of CZ Si, VOn (n=2–4) formation and annihilation was observed.

Numerical analysis of low frequency noise propagation from outdoor into house

There have been increasing environmental problems caused by low-frequency noise: window rattle, human annoyance and so on. Sound transmission from outdoor into a house in the low-frequency range is a considerably complex phenomenon because the house behaves as a total vibrating system composed of windows, walls, frames, ventilation holes, and so on. This paper presents a finite element model of a simple house in order to investigate the low-frequency sound transmission. The features of the model are as follows: 1) a rigid hollow cube with an aperture on its one side is placed on a rigid plane, 2) a windowpane mounted on the aperture is modeled as a limp membrane or an elastic plate, 3) the outdoor domain is truncated by perfectly matched layers in order to simulate a semi-free field, and 4) a noise source is supposed to be an air conditioning outdoor unit placed near the house. It is confirmed that the indoor SPL gains mainly due to two resonance systems: one is the global motion composed of indoor air ti...

Acoustic Property Simulation for Building Components

This chapter shows practical examples of numerical simulation results for acoustical characteristics of building elements, such as the sound absorption, sound-scattering, and sound insulation performance. Additionally, radiation characteristics of speaker systems are also treated. In each section, methodologies and numerical modeling schemes of the simulation, and the calculated results for practical cases are illustrated. The results are validated through comparison with the measurement results, and the applicability of the numerical methods is discussed.

Numerical models for predicting absorption/insulation performance of acoustic elements

WIth a great improvement of computer resource availability, numerical analysis is widely used to investigate acoustic characteristics of various materials. A further expectation will be to predict absorption/insulation performance of acoustic elements used for buildings, automobile and so on, which can be the alternative to the actual measurements. This paper presents general numerical models for predicting the absorption coefficient and the transmission loss of acoustic elements with arbitrary shape and material composition. The features of the models are :1) A test sample is mounted in the cavity or aperture on a thick rigid baffle :2) FEM is employed for the materials and the air in the cavity, and coupled with sound fields out of the baffle by BEM :3) Acoustical indices are calculated from the incidence power and the absorption/transmission power on the interfaces. Numerical simulation demonstrates the oblique incidence absorption coefficients and transmission losses of single layered materials. The i...

Estimation of radiation-induced complex concentration in CZ-Si by IR absorption spectroscopy

Introduction Irradiation-induced complexes are used to fabricate switching devices for hybrid cars [1]. We have established the highly sensitive infrared absorption (IR) measuring method of the absorption lines from the complexes down to 10 in unit of absorbance and detected most kinds of complexes induced in low dose irradiated device grade Si substrates [2]. It is helpful if the complex concentration can be estimated from the absorbance, but there have been few attempts. In this paper we try to estimate the complex concentration.