Abstract: Provided is a culture substrate having a periodic fine structure in the order of micrometers and a periodic fine structure in the order of nanometers on the same surface where stem cells are to be cultured on the surface.

Abstract: The invention provides a method for separating semiconductor light-emitting devices formed on a substrate. In the method, a pulse laser beam having a pulse width less than 10 ps in a substrate is focused on the substrate, to thereby cause multi-photon absorption in the substrate. Through multi-photon absorption, a groove is formed through the pulse laser beam along a split line predetermined on a surface of the substrate, the groove being substantially continuous in the direction of the predetermined split line. In addition, internal structurally changed portions are formed through the pulse laser beam at a predetermined depth of the substrate on a predetermined split face, the structurally changed portions being discontinuous in the direction of the predetermined split line.