Multifunctional Nanocrystalline Thin Films of Er2O3: Interplay between Nucleation Kinetics and Film Characteristics

• Published in: Advanced functional materials Vol. 17; no. 17; pp. 3607 - 3612
• Main Authors: Losurdo, M., Giangregorio, M. M., Capezzuto, P., Bruno, G., Toro, R. G., Malandrino, G., Fragalà, I. L., Armelao, L., Barreca, D., Tondello, E., Suvorova, A. A., Yang, D., Irene, E. A.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 23-11-2007; WILEY‐VCH Verlag
• Subjects: Chemical vapor deposition; Dielectrics; inorganic; Nanocrystalline materials; Thin films; Thin films, inorganic
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.200700524

In this study, thin films of Er2O3 are deposited by low‐pressure metal–organic chemical vapor deposition (MOCVD) using a tris(isopropylcyclopentadienyl)erbium precursor and O2 on various substrates, including p‐type Si(100), Si(111), Corning glass, and c‐axis‐oriented α‐Al2O3(0001). The resulting films are extensively characterized in order to demonstrate their applicability as antireflective and protective coatings and as high‐k gate dielectrics. The interplay existing among the substrate, the nucleation kinetics, and the resulting structural, morphological, optical, and electrical properties of Er2O3 thin films is explored. Fast nucleation governed by surface energy minimization characterizes the growth of (111)‐oriented Er2O3 on Si(100), glass, and α‐Al2O3. Conversely, nonhomogeneous nucleation leads to polycrystalline Er2O3 on Si(111) substrates. Er2O3 films grown on Si(100) possess superior characteristics. A high refractive index of 2.1 at 589.3 nm, comparable to the value for bulk single crystalline Er2O3, a high transparency in the near UV‐vis range, and an optical bandgap of 6.5 eV make Er2O3 interesting as an antireflective and protective coating. A static dielectric constant of 12–13 and a density of interface traps as low as 4.2 × 1010 cm2 eV–1 for 5–10 nm thick Er2O3 layers grown on Si(100) render the present Er2O3 films interesting also as high‐k dielectrics in complementary metal oxide semiconductor (CMOS) devices.
Thin films of Er2O3 are deposited by low‐pressure metal–organic chemical vapor deposition (MOCVD) on various substrates, including p‐type Si(100), Si(111), Corning glass, and α‐Al2O3(0001). The high dielectric values determined (see figure) confirm the high quality of the prepared films. The applicability of the prepared films as antireflective and protective coatings and as a high‐k gate dielectrics in CMOS devices is demonstrated.