Influence of composition and processing parameters on the properties of solution-processed aluminum phosphate oxide (AlPO) thin films

Abstract

The effects of precursor solution concentration, composition, and spin-processing parameters on the thickness and electrical properties of ultra-smooth aluminum oxide phosphate (Al 2 O 3-3x (PO 4 ) 2x or -AlPO‖) thin films prepared using aqueous solutions are reported. Compositions were verified by electron probe micro-analysis and range from Al 2 O 1.5 (PO 4 ) to AlPO 4 (x = P:Al from 0.5-1.0). Film thicknesses were determined using X-ray reflectivity measurements and were found to depend systematically on solution concentration, P:Al ratio, and spin-speed.Metal-insulator-semiconductor devices were fabricated to determine electrical properties as a function of composition. As the P:Al ratio increased from 0.5 to 1.0, the dielectric constant decreased from 6.0 to 4.6, leakage currents increased from 0.45 to 65 nA cm -2 at 1MV cm -1 and dielectric breakdown (defined as leakage currents >10 µA cm -2 ) decreased from 9.74 to 2.84 MV cm -1 . These results establish composition, concentration, and spin-speed for the production of AlPO films with targeted thicknesses and electrical properties.

Low-temperature fabrication of lithium aluminum oxide phosphate solid electrolyte thin films from aqueous precursors

“…These results are consistent with other studies of Al-P-O lms produced using PIC. 28 Lithium ion conductivities of the LiAlPO lms were determined using impedance spectroscopy. Fig.…”

“…The high frequency dielectric constant is near 6, which is slightly above that of AlPO, and it is thickness independent. 28 In addition to the longrange motion of lithium ions that contribute to ionic double layer formation at the electrodes, lithium displacements over shorter ranges contribute to the bulk dielectric constant at higher frequencies leading to an increased dielectric constant relative to AlPO.…”

High Quality Magnetic Oxide Thin Films Prepared via Aqueous Solution Processing

“…Film thickness is predominantly defined by the metal ion concentration of the precursor solution and the annealing temperature, and can be finetuned by adjusting the spin coating parameters. 56 Using a 1.5 M precursor solution, CFO film thicknesses for films annealed at 400°C, 600°C and 800°C were (68 ± 1) nm, (59 ± 1) nm and (48 ± 1) nm, respectively.…”

“…This method, recently coined "Prompt Inorganic Condensation", or PIC, has been used to make high quality films of a number of oxides, including dielectrics, [53][54][55][56][57][58] transparent conducting oxides, 59,60 and high-resolution inorganic resists. 61,62 In these examples using PIC, dehydration and nitrate removal are shown to occur without negatively affecting film morphology, allowing the preparation of dense, smooth films at relatively low temperatures.…”

“…To overcome the limitations of previous wet-chemical approaches, we utilize a method to effectively prepare smooth thin films of metal oxides by spin coating them from aqueous precursor solutions with subsequent annealing. This method, recently coined “Prompt Inorganic Condensation”, or PIC, has been used to make high quality films of a number of oxides, including dielectrics, − transparent conducting oxides, , and high-resolution inorganic resists. , In these examples using PIC, dehydration and nitrate removal are shown to occur without negatively affecting film morphology, allowing the preparation of dense, smooth films at relatively low temperatures. We show that the electronic, optical, and magnetic properties of the nanocrystalline films prepared in this work are comparable to those achieved by vapor phase deposition techniques.…”