Modification of transparent conductive ZnO and Ga-doped ZnO films by irradiation with electron cyclotron resonance argon plasma

Abstract

By irradiating undoped ZnO and Ga-doped ZnO (GZO) films with electron cyclotron resonance Ar plasma, their electrical and optical properties have been modified. Both the carrier concentration and the Hall mobility increased with continuous irradiation in conductive ZnO films with a defect-rich crystalline lattice. Improved crystallinity was verified by intensifying the ZnO(002) x-ray diffraction peak and increasing the optical transmission level in the visible wavelength. This observation suggests network rearrangement through Zn atoms at interstitials or grain boundaries being oxidized or accommodated into the crystalline network. For insulating ZnO films that contain a sufficient number of oxygen atoms, the changes were better scaled with sheet resistance rather than resistivity. The interference fringes redshifted without lowering the transmittance level. Here, Ar ion impact will create oxygen vacancy donors in the near-surface region or desorb interstitial oxygen atoms that act as donor killers. In contrast, GZO films with resistivities in the 10−4 Ω cm range revealed little changes because there were very few imperfections in the crystalline lattice. The reduced amount of resistivity corresponded to the creation of oxygen vacancies in more resistive GZO films in the 10−3 Ω cm range.

Effective Oxygen-Defect Passivation in ZnO Thin Films Prepared by Atomic Layer Deposition Using Hydrogen Peroxide

“…Recently, n-type ZnO with high carrier concentration, high Hall mobility, and low resistivity could be prepared using various doping elements (doping with Cl, Ti, Al, Ga, and N). [12][13][14][15][16] However, the preparation of p-type ZnO with high carrier concentration and conductivity remains an unsolved problem, which prevents the commercial application of ZnO-based LEDs. 4,17) The presence of oxygen vacancies (V o ) in ZnO is one of the main barriers to preparing high-quality p-type ZnO.…”

Transmission/absorption measurements for in situ monitoring of transparent conducting Ga:ZnO films grown via aqueous methods

“…Recent technological demand for thin lms of ZnO in applications such as sensors, emission displays, photovoltaics, piezoelectronics, transparent conductors and solid-state lighting applications [1][2][3][4][5][6][7][8][9][10] has spurred the development of synthesis techniques based on low-temperature aqueous phase processes. Furthermore, exible electronics that require lms to be deposited on plastic substrates will likewise benet from the low synthesis temperatures (<100 C) that are maintained throughout the deposition process.…”