Impact of annealing on the chemical structure and morphology of the thin-film CdTe/ZnO interface J. Appl. Phys. 116, 024312 (2014); 10.1063/1.4890235 Fabrication of ZnO photonic crystals by nanosphere lithography using inductively coupled-plasma reactive ion etching with CH 4 / H 2 / Ar plasma on the ZnO/GaN heterojunction light emitting diodes J. Vac. Sci. Technol. A 28, 745 (2010); 10.1116/1.3357282 Evolution of surface morphology of dry-etched ZnO with Cl 2 / Ar plasma J.Inductively coupled plasma reactive ion etching of bulk ZnO single crystal and molecular beam epitaxy grown ZnO filmsEtching characteristics of ZnO are investigated by means of inductively coupled plasma ͑ICP͒ reactive ion etching in BCl 3 -based plasmas. Etch rates are studied as a function of BCl 3 /Cl 2 /Ar chemistries, substrate temperature, ICP coil power, rf power, and working pressure. Surface profilometer, scanning electron microscopy, and atomic force microscopy are used to characterize etch rates, etch profiles, and the surface morphologies of etched samples. It is shown that the etch rate is determined by the BCl 3 content in the plasma. Auger electron spectroscopy results demonstrate that the BCl 3 -based etching process produces negligible changes in the surface stoichiometry of ZnO.

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We have investigated Al/Pt ͑20/50 nm͒ ohmic contacts on a n-type zinc oxide ͑ZnO:Al͒ epitaxial layer. The samples were annealed at temperatures of 300°C and 600°C for 1 min in nitrogen ambient. Current-voltage measurements indicated that the as-deposited sample was ohmic with a specific contact resistivity of 1.25 (Ϯ0.05) ϫ 10 Ϫ5 ⍀ cm 2 . However, the annealing at 300°C resulted in a significantly better ohmic behavior, with a contact resistivity of 2 (Ϯ0.25) ϫ 10 Ϫ6 ⍀ cm 2 . A further increase in the annealing temperature to 600°C led to a decrease in specific contact resistivity due to extensive interfacial reactions between Al and ZnO. Both Auger electron spectroscopy and glancing angle X-ray diffraction were employed to investigate the nature of the interfacial reaction between the Al/Pt and ZnO layer with increasing annealing temperature. Possible explanation is given to describe the temperature dependence of the specific contact resistivity.ZnO and related oxide semiconductors, such as MgZnO and CdZnO, have acquired considerable importance as the basis for a new generation of optoelectronic devices due to their wide direct bandgap (E g ϭ 3.37 eV), and large exciton binding energy of 60 meV at room temperature, which is much higher than that of GaN ͑25 meV͒ and ZnSe ͑18 meV͒. 1-4 ZnO is an alternate candidate for optoelectronic applications, for use in the short wavelength range ͑green, blue, UV͒. 5 Although great progress has been achieved in the area of ZnO-based oxide semiconductors, many problems remain, such as the difficulty of p-ZnO growth and lack of high quality ohmic or Schottky contacts for n, p-ZnO. In particular, to realize commercialized ZnO-based optoelectronic devices, high quality ohmic and Schottky contacts are required. Several groups have reported ohmic contact schemes, however, most work is the initial stages. Akane et al. investigating In ohmic contacts to undoped n-ZnO, demonstrated that a postannealing treatment for 1 min at 300°C resulted in ohmic contact with a specific contact resistivity of 7 ϫ 10 Ϫ1 ⍀ cm 2 . 6 Kudo et al. fabricating transparent n-ZnO/p-SrCu 2 O 2 junction diode, employed n ϩ -ZnO and ITO as n-type and p-type electrodes, respectively. 2 In our previous studies, we reported on Au, Ti/Au, and Ru ohmic contact scheme with specific contact resistivity of 10 Ϫ3 -10 Ϫ5 ⍀ cm 2 . 7-9 Recently, an Al ohmic scheme was used for a metal-semiconductor-metal device structure and p-n homojunction diodes. 4,10 Although the Al have been used as n-type ohmic contact metal, there are still lack of detailed interfacial reaction study between Al and ZnO. In addition, the detailed electrical and structural examinations of the Al/Pt ohmic schemes have not been hitherto performed.In this work, we reported on electrical and structural examination of Al/Pt multilayer on Al-doped ZnO epitaxy layer with increasing annealing temperature. Using glancing angle X-ray diffraction ͑GXRD͒ and Auger electron spectroscopy ͑AES͒ depth profiles analysis, we suggested possible mechanism to describe tem...