Preparation and characterization of phosphorus-doped aluminum oxide thin films

Aluminum oxide thin films with or without phosphorus doping were deposited by the atomic layer epitaxy (ALE) technique. The source materials for aluminum were aluminum chloride and aluminum n-propoxide and for oxygen, water and 2-methyl-2-propanol. The phosphorus source was P2O5. The films were analyzed by Rutherford backscattering spectroscopy (RBS), nuclear resonance broadening (NRB), X-ray diffraction (XRD), X-ray fluorescence (XRF), and Fourier transform infrared (FTIR) spectroscopy for chemical composition and structure. The results show that phosphorus can be incorporated in a wide range of concentration levels into the aluminum oxide layers. Greater than 20 wt% doping, however, led to the formation of crystalline aluminum phosphate when the oxygen source was 2-methyl-2-propanol. The phosphorus doping also increased the growth and H3PO4 etch rates of the films.