A nitride semiconductor substrate having a rugged surface being lapped by whetting granules to roughness between Rms5 nm and Rms200 nm, which has a function of reducing dislocations of a GaN, InGaN or AlGaN layer epitaxially grown on the lapped substrate by gathering dislocations in the epi-layer to boundaries of holes, pulling the dislocations to bottoms of the holes. The method includes detecting the position of the markers arranged on the device and ascertaining data for registering the hip. The main portion of the lower contact pin includes two elastic arms, and each elastic arm has a first and a second locking protrusions engaging with a slot defined on the guiding portion of the upper contact pin respectively to reliably connect the upper contact pin and the lower contact pin.