Abstract: A semiconductor device includes: a semiconductor substrate, the semiconductor substrate comprising; an n type drift layer, a p type body layer on an upper surface side of the drift layer, and a high impurity n layer on a lower surface side of the drift layer. The high impurity n layer includes hydrogen ion donors as a dopant, and has a higher density of n type impurities than the drift layer. A lifetime control region including crystal defects as a lifetime killer is formed in the high impurity n layer and a part of the drift layer. A donor peak position is adjacent or identical to a defect peak position, at which a crystal defect density is highest in the lifetime control region in the depth direction of the semiconductor substrate. The crystal defect density in the defect peak position of the lifetime control region is 1×1012 atoms/cm3 or more.

Abstract: In a two-way clutch comprising an outer race having a plurality of roller receiving portions each formed by a pair of bisymmetrical arch-shaped cam surfaces, rollers disposed in the roller receiving portions, and a cage having support portions for the rollers and disposed on the inner periphery side of the outer race, the cage has a portion extending in the direction of a rotary shaft and clutch shoe receiving portions radially provided on the extending portion, and clutch shoes slidably fitted in the clutch shoe receiving portions have a sliding surface displaced by a centrifugal force resulting from the rotation of the clutch and sliding relative to a member outside the clutch.