[en] In 1998 fiscal year, in order to elucidation on contribution of electron excitation effect in crystal growth of a semiconductor under succession of the previous fiscal year, an investigation to elucidate electron excitation effect in semiconductor solid phase growth by photon in UV region was carried out, to find out that UV radiation promoted solid phase growth of Si and to elucidate that the electron excitation effect shared an important part on ion beam induced crystal growth. Therefore, in order to investigate feasibility on application of the ion beam induced crystal growth method to crystalline materials with larger band gap, a study on ion beam induced crystal growth of diamond with maximum band gap (5.5 eV) for a semiconductor material was initiated. As a result, it was elucidated that the ion beam induced crystal growth method was also effective for diamond. (G.K.)