Measurements of the Hall coefBcient and resistivity for highly oriented TlqBa2CaCu208+p thin films are reported. The temperature dependence of cotO~, where O~is the normal-state Hall angle, for a single-phase (2:2:1:2)film sample and for other Tl-based phases is found to be linear in T . This behavior is in agreement with recent predictions based on Anderson s spinon-holon model, but it is surprisingly general since it still holds for samples in which the resistivity does not follow Anderson's predicted linear behavior and in which superconductivity is partially or completely suppressed.The normal-state electron-transport properties of the high-temperature superconducting oxides present an anomaly. i z None of the transport coefficients has been more puzzling than the Hall effect. 3 The family of Tl-based high-T, oxides with its high number of stoichiometric phases Tl BazCa" iCu"Oz"+~+z (m=1,2; n=l, 2, 3,4), most of which are superconducting, offers a unique system for study of normal-state transport. In particular, measurements of the anisotropic transport coefficients (in the ab plane and along the c axis) for the different phases and their derivatives that can be produced by selective site doping would be very useful. Singlecrystal Hall measurements have been reported, however, only for the (2:2:0:1)phase and its variations produced by doping with excess oxygen. 4 We report Hall coefficient and resistivity measurements for thin-film (2:2:1:2)samples that are highly oriented with the c axis normal to the substrate. Consequently, the measurements are expected to correspond to transport in the ab plane of a single-crystal sample.The thin Blms have been grown using an amorphous BaCaCu alloy precursor which has been thermally oxidized and into which Tl has been difFused at high temperature to grow the oriented (2:2:1:2)films. This technique for production of oriented films has been described in detail previously. 5 7 X-ray diffraction scans for two films, A and B, are shown in Fig. 1. Both show a high degree of orientation with the c axis aligned normal to the single-crystal MgO (100) substrate. Based on the xray diffraction patterns, film B is essentially single phase (2:2:1:2) whereas a small amount of (2:2:2:3)phase can be readily identified in the x-ray pattern for A.A four-terminal method was used for the resistance measurements while the Hall coeKcient was measured with a three-terminal configuration which allowed electrical alignment of the Hall probes by balancing the potentiometer across the two Hall electrodes on one side to null the voltage when the Beld was zero. Measurements were taken at Bxed temperatures as a function of field up to 6 T. The thicknesses of the films were measured with an alpha-step profilometer. The Blms were rough; consequently, the average value of thickness was used.Further uncertainties in the thickness measurement may arise because of a nonconducting Tlp03 layer on the top surface which might result from the Tl diffusion process and a possible dead layer on the bottom surface f...