We have studied stable structures of hydrogenated Si clusters grown from silane gas in an ion trap developed for cluster growth. The grown clusters were extracted from the ion trap through two different pathways and were analyzed by mass spectrometers. The Si6Hx+ cations were stably grown, among them clusters with x = 1, 7, and 13 were always observed, regardless of the growth conditions or the extraction pathways. The stable structures of these clusters were theoretically investigated. Clusters of x = 1, 7, and 13 corresponded to the compact structure, the intermediate structure which has both compact and bulklike configurations, and the bulklike sp3 structure, respectively. © 1997 American Institute of Physics.