Large-diameter (2-inch), n-type ZnO boules grown by a new vapor-phase transport method were investigated by the temperature-dependent Hall-effect technique. The 300-K Hall carrier concentration and mobility were about 6 x 10(16) cm(-3) and 205 cm(2) V-1 s(-1) respectively, and the peak mobility (at 50K) was about 2000 cm(2) V-1 s(-1), comparable to the highest values reported in the East for ZnO. The dominant donor had a concentration of about 1 x 10(17) cm(-3) and an energy of about 60 meV, close to the expected hydrogenic value, whereas the total acceptor concentration was much lower, about 2 x 10(15) cm(-3). Photoluminescence measurements confirm the high quality of the material. (C) 1998 Elsevier Science Ltd.