A nonalloy Ohmic electrode is formed on a hydrothermally grown n-type ZnO substrate by KrF excimer laser irradiation and metal deposition without any impurity doping. Laser irradiation changes the ZnO surface layer to a Zn-rich one with lower sheet resistance than the bulk. The Zn-rich premetallized layer (ZnOx layer, x = 0-1) exhibits n(+)-type conduction, which enables current conduction into the ZnO substrate with Ohmic characteristics. An In/ZnOx contact fabricated by single-pulse laser irradiation with 0.3. J/cm(2) on the ZnO substrate has a contact resistance of 7 X 10(-1) Ohm cm(2). A postheat treatment for 5 min at 300 degrees C increases the sheet resistance in the premetallized layer, which causes an increase of the contact resistance of the fabricated contact.