Ga-doped ZnO films were deposited by pulsed laser deposition (PLD) at 200 degrees C and 10 mTorr in either pure argon (Ar films) or in oxygen (O-2 films). The bulk resistivity of the Ar films is 10(-4) Omega cm at 300 K, two orders of magnitude lower than that of the O-2 films. In the Ar films, the donor concentration N-D as determined by a detailed Hall-effect analysis is close to 100% of the total Ga concentration [Gal measured by secondary ion mass spectrometry (SIMS), while in the O-2 films ND is less than 50% of [Gal. Furthermore, the compensation ratio K=N-A/N-D is >90% for the O-2 films and