Effects of O7+ swift heavy ion irradiation on indium oxide thin films

Indium oxide thin films deposited by spray pyrolysis were irradiated by 100 MeV O7+ ions with different fluences of 5 × 1011, 1 × 1012 and 1 × 1013 ions/cm2. X-ray diffraction analysis confirmed the structure of indium oxide with cubic bixbyite. The strongest (2 2 2) orientation observed from the as-deposited films was shifted to (4 0 0) after irradiation. Furthermore, the intensity of the (4 0 0) orientation was decreased with increasing fluence together with an increase in (2 2 2) intensity. Films irradiated with maximum fluence exhibited an amorphous component. The mobility of the as-deposited indium oxide films was decreased from ∼78.9 to 43.0 cm2/V s, following irradiation. Films irradiated with a fluence of 5 × 1011 ions/cm2 showed a better combination of electrical properties, with a resistivity of 4.57 × 10−3 Ω cm, carrier concentration of 2.2 × 1019 cm−3 and mobility of 61.0 cm2/V s. The average transmittance obtained from the as-deposited films decreased from ∼81% to 72%, when irradiated with a fluence of 5 × 1011 ions/cm2. The surface microstructures confirmed that the irregularly shaped grains seen on the surface of the as-deposited films is modified as “radish-like” morphology when irradiated with a fluence of 5 × 1011 ions/cm2.

► The structural, morphology and electrical properties of indium oxide thin films.
► From the XRD, the ion irradiation has changed the preferred orientation from (2 2 2) to (4 0 0).
► RMS roughness is significantly reduced to 10 nm for an ion fluency of 1 × 1013 ions/cm2.
► The mobility of ion irradiated films (1 × 1013 ions/cm2) is decreased from 76.6 to 43 cm2/V s.
► The average transmittance (400–2500 nm) of the as-deposited IO film is decreased from 81% to 72% after SHI irradiation.