Structural change of amorphous silicon induced by X-ray irradiation from synchrotron radiation

Using synchrotron radiation, amorphous silicon (a-Si) films were irradiated by X-rays with photon energy large enough to excite K-shell electrons in silicon. Electron spin resonance measurements showed that the effective formation efficiency of dangling bonds per X-ray photon was seven to eight orders of magnitude larger than that for the conventional light soaking using laser light. Photoconductivity and positron lifetime measurements indicated that, besides the dangling bonds, microvoid-like defects are induced by X-ray irradiation. The enhancement of the solid-phase crystallization of a-Si by X-ray irradiation is discussed on the basis of such structural change.