Patent ID: 8283865

Claim:
An excimer discharge lamp comprising: an electric discharge container including a pair of plates which face each other, wherein an electrical discharge space is formed between the pair of the plates; a pair of external electrodes provided on exterior surfaces of the pair of the plates; and a light emission gas which is enclosed in the electrical discharge space, wherein the light emission gas is at least one selected from a group consisting essentially of rare gas and halogen, and halide; wherein the electrical discharge space of the electric discharge container is sealed by the pair of the plates and a side wall which connects the pair of the plates, wherein the pair of the plates and the side wall are made of at least one of a group consisting essentially of sapphire, YAG, and single crystal yttria, wherein impurities which exist in an inner surface of the electric discharge container surrounding the electrical discharge space consist of at least one of silicon, carbon and cerium; and the quantity of the impurities is 0.6 ng/cm 2 or less.