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

In this study, thin films of Er 2 O 3 are deposited by low‐pressure metal–organic chemical vapor deposition (MOCVD) using a tris(isopropylcyclopentadienyl)erbium precursor and O 2 on various substrates, including p‐type Si(100), Si(111), Corning glass, and c ‐axis‐oriented α‐Al 2 O 3 (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 Er 2 O 3 thin films is explored. Fast nucleation governed by surface energy minimization characterizes the growth of (111)‐oriented Er 2 O 3 on Si(100), glass, and α‐Al 2 O 3. Conversely, nonhomogeneous nucleation leads to polycrystalline Er 2 O 3 on Si(111) substrates. Er 2 O 3 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 Er 2 O 3 , a high transparency in the near UV‐vis range, and an optical bandgap of 6.5 eV make Er 2 O 3 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 × 10 10 cm 2 eV –1 for 5–10 nm thick Er 2 O 3 layers grown on Si(100) render the present Er 2 O 3 films interesting also as high‐ k dielectrics in complementary metal oxide semiconductor (CMOS) devices.