E. Elangovan

Spray deposited molybdenum doped indium oxide thin films with high near infrared transparency and carrier mobility

Molybdenum doped (0–1 at. %) indium oxide thin films with high near infrared (NIR) transparency and carrier mobility were deposited on Corning-1737 glass substrates at 400 °C by spray pyrolysis experimental technique. Films with mobility as high as ∼149 cm2/V s were obtained when annealed in vacuum at 550 °C, which also possess carrier concentration of ∼1×1020 cm−3 and resistivity as low as ∼4.0×10−4 Ω cm. Further, both the average visible transmittance (500–800 nm) and the average NIR transmittance are >83%. This clearly shows that the transmittance is extended well into the NIR region.

p-Type

Thin-films of copper oxide (Cu<i>x</i>O) were sputtered from a metallic copper (Cu) target and studied as a function of oxygen partial pressure (O_PP). A metallic Cu film with cubic structure obtained from 0% O_PP has been transformed to cubic Cu₂O phase for the increase in O_PP to 9% but then changed to monoclinic CuO phase (for O_PP ≥ 25%). The variation in crystallite size (calculated from x-ray diffraction data) was further substantiated by the variation in grain size (surface microstructures). The Cu<i>x</i>O films produced with O_PP ranging between 9% and 75% showed p-type behavior, which were successfully applied to produce thin-film transistors.

{\hbox{Cu}}_{x}{\hbox{O}}

Molybdenum (0–1 at. %) doped indium oxide thin films with high near-infrared (NIR) transparency and high carrier mobility were deposited on Corning-1737 glass substrates at 400 °C by a spray pyrolysis experimental technique. X-ray diffraction (XRD) analysis confirmed the cubic bixbyite structure of indium oxide. The preferred growth orientation along the (222) plane for the low Mo doping level (≤0.5 at. %) shifts to (400) for higher Mo doping levels (>0.6 at. %). The crystallite size extracted from the XRD data corroborates the changes in full width at half maximum due to the variation in Mo doping. A scanning electron microscopy study illustrated the evolution in the surface microstructure as a function of Mo doping. The negative sign of the Hall coefficient confirmed the n-type conductivity. A high carrier mobility of ∼122.4 cm2/V s, a carrier concentration of ∼9.5×1019 cm−3, a resistivity of ∼5.3×10−4 Ω cm, and a high figure of merit of ∼4.2×10−2 Ω−1 are observed for the films deposited with 0.5 at. % ...

Films Deposited at Room Temperature for Thin-Film Transistors

The high visible–near infrared transparent and high carrier mobility (μ) Mo doped (0.5 at%) indium oxide (IMO) films were deposited by the spray pyrolysis technique. The deposited films were irradiated by 50 MeV Li3+ ions with different fluences of 1 × 1011, 1 × 1012 and 1 × 1013 ions cm−2. X-ray diffraction analysis confirmed the cubic bixbyite structure of indium oxide. A fascinating feature is that the ion irradiation process has introduced a fraction of the molybdenum oxide phase. The μ of as-deposited IMO films is decreased from ~122.4 to 93.3 cm2 V−1 s−1, following the ion irradiation. The theoretically calculated μ and carrier density values were correlated with those measured experimentally. The transport mechanism has been analysed based on the ionized and neutral impurity scattering centres. The average transmittance (400–2500 nm) of the as-deposited IMO films is decreased from 83% to 60% following irradiation.

High near-infrared transparency and carrier mobility of Mo doped In2O3 thin films for optoelectronics applications

Abstract N-doped ZnO films were radio frequency (RF) sputtered on glass substrates and studied as a function of oxygen partial pressure (OPP) ranging from 3.0×10 −4 to 9.5×10 −3 Pa. X-ray diffraction patters confirmed the polycrystalline nature of the deposited films. The crystalline structure is influenced by the variation of OPP. Atomic force microscopy analysis confirmed the agglomeration of the neighboring spherical grains with a sharp increase of root mean square (RMS) roughness when the OPP is increased above 1.4×10 −3 Pa. X-ray photoelectron spectroscopy analysis revealed that the incorporation of N content into the film is decreased with the increase of OPP, noticeably N 1s XPS peaks are hardly identified at 9.5×10 −3 Pa. The average visible transmittance (380-700 nm) is increased with the increase of OPP (from ∼17% to 70%), and the optical absorption edge shifts towards the shorter wavelength. The films deposited with low OPP (≤ 3.0×10 −4 Pa) show n-type conductivity and those deposited with high OPP (≥ 9.0×10 −4 Pa) are highly resistive (>10 5 Ω·cm)

Effect of Li3+ heavy ion irradiation on the Mo doped In2O3 thin films prepared by spray pyrolysis technique

In the present work, the spectroscopic ellipsometry (1.5 - 5.5 eV) was used to investigate the effects of current density induced microstructural variations and their influence on the electronic states of as-prepared and a-Si:H coated porous silicon (PS). The pseudodielectric responses of the low and high current densities (5 and 40 mA/cm2) were analyzed using a multilayer model within the effective medium approximation. The FTIR investigation reveals the enhancement of surface oxide (Si-Ox) layer with current density and the improvement of the Si-Hx band after a-Si:H coating.