Nanostructured n-type bismuth telluride (Bi₂Te₃) thin films were grown on SiO₂/Si (1 0 0) substrates at argon ambient pressure (P_Ar) of 80 Pa by pulsed laser deposition (PLD). The effects of film morphologies, structures, and compositions on the thermoelectric properties were investigated. At a substrate temperature (T_s) of 220–340 °C, stoichiometric films with highly (0 0 l)-oriented and layered structures showed the best properties, with a carrier mobility μ of 83.9–122.3 cm²/Vs, an absolute Seebeck coefficient |α| of 172.8–189.7 μV/K, and a remarkably high power factor (PF) of 18.2–24.3 μW cm⁻¹ K⁻². By contrast, the Te-rich films deposited at T_s ⩽ 120 °C with (0 1 5)-preferred orientations and columnar-small grain structures or the Te-deficient film deposited at 380 °C with Bi₄Te₅ polyhedron structure possessed poor properties, with μ < 10.0 cm²/Vs, |α| < 54 μV/K, and PFs ⩽ 0.44 μW cm⁻¹ K⁻². The morphology of highly (0 0 l) oriented-layered structures and the stoichiometry predominantly contribute to the substantial enhancement of μ and |α|, respectively, resulting in remarkable enhancement in PF.