We synthesized c-axis-oriented Mg1-xAlxB2 thin film on an Al buffered layer of c-cut Al2O3 substrate via hybrid physical-chemical vapor deposition (HPCVD) and measured the longitudinal and Hall resistivities in the ab- plane. X-ray diffraction (XRD) showed the shift of the (000l) MgB2 peaks to higher 2 theta values, indicating that Al was substituted for Mg. The 185-nm Mg1-xAlxB2 showed a critical temperature (Tc) of 26.8 K with a broadened transition width of approximately 11 K. In the normal state, the Hall coefficient was positive and decreased as the temperature increased. At T = 100K, Hall coefficient (RH) is 18.97 x 10_ 11 m3/C, from which the hole charge carrier density (nhole) was determined to be 3.29 x 1022 holes/cm3. The suppression of nhole compared to pure MgB2 of approximately 2 x 1023 holes/cm3 supported the hypothesis that Al3+ substitutes to Mg2+. In the superconducting state, universal Hall scaling behavior with a constant beta of 1.7 +/- 0.2 was observed due to the appearance of Al impurities.
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