Pure and mixed phase Bi₂O₃ thin films obtained by metal organic chemical vapor deposition

Abstract

Bismuth oxides have important catalytic properties in oxidation reactions such as ammoxidation for the synthesis of acrylonitrile from propylene, oxygen, and ammonia. Such powerful catalytic activity appears to be correlated with the existence of variable oxidation states of bismuth and with the high oxygen mobility on the surface. Bismuth(r1r) oxide also has many different technical applications such as Schottky barrier solar cells, optical coatings, and dielectric materials in metal insulator semiconductor capacitors."] Therefore, taking into account both the reactivity of the surface and the electrical properties, bismuth oxide in the form of films or thin films can also find important applications in gas sensor devices.However, since the phase and morphology of the films strongly affect the functional properties, we carried out the synthesis of pure Biz03 thin films with the aim of studying the influence of the substrate and of the process parameters on the growth modality and structure of the coatings.The Bi-0 system is rather complicated and can have four different main crystalline phases, usually indicated with the letters a, p, y, and 6. Only the aand P-Bi2O3 phases are well characterized, since they are stable at room temperature, while the y and 6 phases can be obtained only at high temperatures ( T > 1003 K for 6 and T > 908 K for y). Each of these phases has different electrical properties, ranging from a typical electronic conduction behavior in the a phase to a perfectly ionic conduction mechanism in the 6 phase.[*]Because of the different electrical properties found in each of the Bi203 phases it is clear that a possible use of bismuth oxide films in gas sensing devices is connected with the possibility of controlling the stoichiometry and the morphology in the deposition procedures. 238 0 VCH Verlagsgcsellschaft mbH, 0-69469 Weinheim, 1996

Fluidized‐Bed MOCVD of Bi2O3 Thin Films from Bismuth Triphenyl under Atmospheric Pressure

“…[1] These properties make Bi 2 O 3 films well suited for many applications such as microelectronics, [2] sensor technology, [3] optical coatings, [4] and ceramic glass manufacturing. [5] Various precursors have been employed to synthesize Bi 2 O 3 films by CVD, including bismuth halides and bismuth triphenyl Bi(Ph) 3 .…”

“…[5] Various precursors have been employed to synthesize Bi 2 O 3 films by CVD, including bismuth halides and bismuth triphenyl Bi(Ph) 3 . [1,2,4,[6][7][8][9][10][11] Halides are known to be toxic and corrosive. Bi(Ph) 3 is safer and offers remarkable advantages in terms of thermal stability and clean sublimation.…”

Synthesis, surface tension, optical and dielectric properties of bismuth oxide thin film

“…Significant applications of bismuth oxides in the fields such as microelectronics [1], sensor technology [2], optical coatings [3], transparent ceramic glass manufacturing [4] have been discovered during the last years. The material is characterized by a large energy band-gap, high photoconductivity, high refractive index, dielectric permittivity and photoluminescence.…”

Crystalline bismuth oxide nanorods fabricated on Pt‐coated substrates using a trimethylbismuth and oxygen mixture

“…Since bismuth oxide (Bi 2 O 3 ) has been known to exhibit remarkably useful solid-state properties including significant energy band gap (2.85 and 2.58 eV for the monoclinic α-Bi 2 O 3 and the tetragonal β-Bi 2 O 3 phases, respectively), high refractive index, high dielectric permittivity, and marked photoconductivity [1][2][3][4], it can be used for optical coatings [5], gas sensor technology [6], microelectronics [7], and ceramic glass manufacturing [8]. In addition, Bi 2 O 3 is a component of various important electroceramic oxides including Bi-Sr-Ca-Cu-O superconductors [9], and SrBi 2 Ta 2 O 9 /SrBi 2 Nb 2 O 9 ferroelectric oxides, which have applications in non-volatile computer memories [10][11][12].…”