Comparative Study of Electronically Controlled Motion of Hydrogen around Carbon and Platinum Atoms in Silicon
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Comparative Study of Electronically Controlled Motion of Hydrogen around Carbon and Platinum Atoms in Silicon Yoichi Kamiura, Namula Bao, Kimihiro Sato, Kazuhisa Fukuda1, Yasuyuki Iwagami, Yoshifumi Yamashita and Takeshi Ishiyama Faculty of Engineering, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan 1 NEC Laboratories, Otsu 520-0833, Japan ABSTRACT We have studied the local motion of hydrogen in the neighborhood of carbon and platinum impurities by observing the stress-induced reorientation and subsequent recovery of two H-related (H-C and Pt-H2) complexes in Si, using deep-level transient spectroscopy (DLTS) under uniaxial compressive stress. We notice two interesting differences in hydrogen motion around carbon and platinum atoms. The first one is a difference in the temperature where stress-induced reorientation occurs. That of the H-C complex occurs at high temperatures above 250 K, while it occurs at low temperatures around 80 K for the Pt-H2 complex. The second difference is the effect of charge state of the complexes on their stress-induced reorientation and subsequent recovery. It occurs preferentially when an electron occupies the level of the H-C complex, but the Pt- H2 complex has the reverse effect of level occupancy. These differences are discussed from viewpoint of different atomic configurations and electronic states of two H-related complexes. INTRODUCTION The static properties of hydrogen in semiconductors, such as electronic state, stable lattice location and configuration, have extensively been studied, but only little information has been obtained on the dynamic properties of hydrogen. Such information as diffusion and local motion around defects and impurities is useful to design electronic devices considering the spatial extent where hydrogen influences the electrical and optical properties of semiconductors. However, hydrogen is so mobile and reactive to other defects and impurities that one cannot detect hydrogen in isolated states but mostly in bound states to other defects and impurities. Few groups have studied the local motion of hydrogen bound to impurities. The dynamical tunneling motion of proton was observed in some systems, H-Si in Ge [1] and H-Be in Si [2]. On the other hand, the hydrogen motion around boron in Si is not pure tunneling but thermally assisted tunneling [3]. Recently, we have found the signatures of electronically controlled motion of hydrogen bound to carbon in Si [4, 5], and observed that hydrogen moves faster in the electron-occupied charge state than in the electron-empty one in the recovery of stress-induced reorientation of the H-C complex. The same charge-state-dependent motion of isolated hydrogen was observed in the recovery of stress-induced reorientation of the AA9 EPR center [6]. More recently, we have observed the completely opposite charge-state-dependence of hydrogen motion around platinum in the Pt-H2 complex in Si [7]. In this paper, we compare electronically controlled motion of hydrogen in the neighborhood of two impurities
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