Electrical and structural properties of low resistivity tin-doped indium oxide films

Abstract

Tin-doped indium oxide (ITO) films with the resistivity less than 1.35×10−4 Ω cm were formed by low voltage dc magnetron sputtering (LVMS) and highly dense plasma-assisted electron beam (EB) evaporation using the arc plasma generator (HDPE). The structural properties of these films were investigated using x-ray diffraction, scanning electron microscope, and electron spectroscopy for chemical analysis, in comparison with the films formed by conventional magnetron sputtering and EB evaporation, in order to clarify the key factors for low resistivity. With decreasing plasma impedance and sputtering voltages from 540 to 380 V, the resistivity of the films deposited at Ts=400 °C decreased from 1.92 to 1.34×10−4 Ω cm, due mostly to increase in the carrier density. This LVMS film showed higher crystallinity because of lower damages of high-energy particles during the deposition, which might increase the number of electrically active species. For HDPE, the film with resistance of 1.23×10−4 Ω cm was deposited at Ts=280 °C, which showed more flat surface morphology and less surface segregation of tin than the conventional EB films.

Transparent Electrodes for Efficient Optoelectronics

“…In terms of deposition, further development of high-end deposition techniques, such as ALD, low-temperature solution-based deposition processes, or new PVD system designs that avoid the direct exposure of the substrate to the plasma during deposition (e.g., high-density plasma-enhanced evaporation, [188,189] or facing target sputtering [190] ), is just one path to the development of ultra-high performance TCOs and TCOs/ device interfaces.…”

Real-time evolution of the indium tin oxide film properties and structure during annealing in vacuum

“…However, under this condition, a satisfactorily low resistivity of the films cannot readily be obtained, [2] so that a deposition on heated substrates or post-deposition annealing is necessary. So far, the annealing processes for reactively sputtered ITO [3,4] have only been studied for metal-rich films, in contrast to comprehensive studies after magnetron sputtering from ceramic targets [5][6][7][8][9][10]. Moreover, mainly isothermal heat treatment is considered in the literature, although annealing using a temperature ramp is of more relevance for practical application.…”

“…This approach requires simplifying assumptions on the linear dependence of the resistivity or reflectivity on the crystalline fraction, and the stability of the film roughness during annealing. Direct investigations of the influence of heat treatment on the ITO film structure are so far limited to post-annealing studies by X-ray diffraction (XRD) and scanning or transmission electron microscopy [3][4][5]7,8,11].…”

High rate deposition of tin-doped indium oxide films by reactive magnetron sputtering with unipolar pulsing and plasma emission feedback systems

“…Sn-doped In 2 O 3 (ITO) is an n-type, highly degenerate, wide-gap semiconductor which, due to its relatively low resistivity and high visible transmittance compared to the other TCO materials such as SnO 2 or ZnO, is at present overwhelmingly used as transparent electrodes in liquid crystal displays (LCDs), plasma displays and light emitting diodes (LEDs) [1][2][3][4][5][6]. Considerable effort has been focused on depositing ITO films of significantly low resistivity in order to accommodate the increasing technological demand for larger area flat panel displays with higher image quality [7][8][9][10][11].…”

“…This method provides the low resistivity of about 10 K4 to 10 K3 Ucm [7,8,[11][12][13][14]. However, the deposition rate, one of the most important factors dominating the deposition cost, is not so high because of the low sputtering yield of the oxide.…”