Reactive ion assisted deposition of aluminum oxynitride thin films

Abstract

Optical properties, stoichiometry, chemical bonding states, and crystal structure of aluminum oxynitride (AlO(x)N(y)) thin films prepared by reactive ion assisted deposition were investigated. The results show that by controlling the amount of reactive gases the refractive index of aluminum oxynitride films at 550 nm is able to be varied from 1.65 to 1.83 with a very small extinction coefficient. Variations of optical constants and chemical bonding states of aluminum oxynitride films are related to the stoichiometry. From an x-ray photoelectron spectroscopy analysis it is observed that our aluminum oxynitride film is not simply a mixture of aluminum oxide and aluminum nitride but a continuously variable compound. The aluminum oxynitride films are amorphous from an x-ray diffraction analysis. A rugate filter using a step index profile of aluminum oxynitride films was fabricated by nitrogen ion beam bombardment of a growing Al film with backfill oxygen pressure as the sole variation. This filter shows a high resistivity to atmospheric moisture adsorption, suggesting that the packing density of aluminum oxynitride films is close to unity and the energetic ion bombardment densifies the film as well as forming the compound.

Structural investigation of high‐transmittance aluminum oxynitride films deposited by ion beam sputtering

“…Apparently, higher BE components appeared in N 1s spectra when P O 2 was 0.9 × 10 −5 Torr or higher. Since the N 1s and Al 2p are the main species in AlON‐0.3, it is reasonable to assign the main N 1s component to be NAl bonds where the BE position of this N component located at 397.4 ± 0.3 eV which is consistent to the BE of N 1s in AlN reported by Wang et al 10 and Rabalais et al 11 Three individual N 1s components were reported in previous studies of aluminum oxynitride films 2, 12, 13…”

“…It is expected that aluminum oxynitride films should have properties between pure AlN and Al 2 O 3 , i.e. exhibit high transmittance, high resistivity, variable refractive indices and high band‐gap energy 1–3. Since the properties of aluminum oxynitride film can be tailored by adjusting the film composition, it is used extensively in optical thin film design, especially in the near‐UV light range 2, 4.…”

“…exhibit high transmittance, high resistivity, variable refractive indices and high band‐gap energy 1–3. Since the properties of aluminum oxynitride film can be tailored by adjusting the film composition, it is used extensively in optical thin film design, especially in the near‐UV light range 2, 4. Our previous studies indicated that the optical properties of aluminum oxynitride films can be fine tuned by changing the P O 2 during the film deposition 5.…”

Role of oxygen contaminant on the physical properties of sputtered AlN thin films

“…Refractive index values in the visible range are slightly lower than those present in the literature for stoichiometric AlN compound [21,22], but they are higher than the values reported in Ref. [23] for thin films as well as the values reported for aluminum oxynitride compounds [24]. AlN60 has the lowest refractive index at l ¼ 630 nm as a consequence of the different chemical composition with respect to the other samples; the highest oxygen contamination observed in this sample is in agreement with the results reported in Ref.…”

Spectrophotometric analysis of aluminum nitride thin films

“…1-5 Furthermore, high solubility with other III-V compounds and good mechanical and thermal matching with substrate materials make AlN a promising component material in the fabrication of optical, [6][7][8] ultraviolet ͑UV͒ optoelectronic, 9,10 high frequency electroacoustic [11][12][13][14] devices, and sensors. 1-5 Furthermore, high solubility with other III-V compounds and good mechanical and thermal matching with substrate materials make AlN a promising component material in the fabrication of optical, [6][7][8] ultraviolet ͑UV͒ optoelectronic, 9,10 high frequency electroacoustic [11][12][13][14] devices, and sensors.…”