A semiconductor device includes a silicon semiconductor body having a main surface and a nitrogen concentration which is lower than about 2*1014 cm\u22123 at least in a first portion of the silicon semiconductor body, the first portion extending from the main surface to a depth of about 50 \u03bcm. The curved display apparatus may more accurately and effectively recognize touch input and thus, user convenience may be improved. It is arranged so that the value of D2D1 is within a range of 0. A locking plate is coupled to the button and configured to move with the button. Ballasts include a multi-channel ballast that enables close-loop control of individual fixtures, or of individual dimmable or non-dimmable lamps within a fixture.