Electronic Structure of Cerium Oxide Gate Dielectric Grown by Plasma-Enhanced Atomic Layer Deposition

We have systematically investigated the electronic structure of CeO 2 dielectric by plasma enhanced atomic layer deposition (PE-ALD). The CeO 2 films were deposited by using novel tris(isopropyl-cyclopentadienyl)cerium [Ce(iPrCp) 3 ] precursor and O 2 plasma. The energy band gap (3.48 eV), Fermi level (4.71 eV), and band offsets of PE-ALD CeO 2 were elaborately determined by combining spectroscopic ellipsometry and ultraviolet photoemission spectroscopy (UPS) techniques. In addition, based on the experimental results of Fowler-Nordheim(F-N) tunneling and Poole-Frenkel(P-F) conduction for Al/PE-ALD CeO 2 /p-Si, the increased interfacial layer and reduced trapped oxide densities were found to be correlated to the increase in effective barrier height (0.89, 1.18 and 1.26 eV) and decrease in decreased trap energy levels (0.47, 0.26 and 0.18 eV) with increasing O 2 annealing temperature (400, 600 and 800°C), respectively. These discrepancies might be attributed to the thin film characteristics and oxygen vacancies in the CeO 2 dielectrics, depending on the deposition techniques and post deposition annealing processes.