Elsevier

Journal of Crystal Growth

Volume 290, Issue 1, 15 April 2006, Pages 156-160
Journal of Crystal Growth

Structure, electrical and optical properties of N–In codoped ZnO thin films prepared by ion-beam enhanced deposition method

https://doi.org/10.1016/j.jcrysgro.2006.01.004Get rights and content

Abstract

N–In codoped ZnO films were prepared on Si, SiO2 and glass substrates by ion-beam enhanced deposition method and their structural, optical and electrical properties were characterized. The polycrystalline N–In codoped ZnO films deposited on Si, SiO2 and glass substrates are found to have a preferred (0 0 2) orientation, smooth surface and high density. The as-deposited ZnO film on Si substrate showed p-type with a resistivity of 2.4 Ω cm. After being annealed in N2 at a temperature lower than 600 °C, the ZnO films showed p-type and the lowest resistivity was 0.8 Ω cm. When the annealing temperature was higher than 600 °C, the ZnO films becomes n-type, and as the annealing temperature goes up, the resistivity of the N–In decreases.

Introduction

Recently great interest has been paid to wide band gap semiconductors, because of the ever increasing commercial desire for short wavelength lasers and blue light-emitting diodes. ZnO has important application potential owing to its diverse superior properties. Its wide band gap of 3.37 eV at room temperature makes ZnO suitable for short-wavelength opto-electronic devices, including light-emitting diodes (LEDs) and laser diodes (LDs). ZnO has an exciton binding energy of 60 meV, which renders it more applicable for making room-temperature UV laser devices. High-quality polycrystalline ZnO film exhibiting a strong photoluminescence (PL) is a prerequisite for the development of ZnO film-based optoelectronic devices. To obtain such ZnO films a variety of techniques may be used, such as molecular beam epitaxy (MBE) [1], [2], [3], (PLD) [4], [5], [6], RF magnetron sputtering [7], [8], [9] and reactive DC sputtering [10], metalorganic chemical vapor deposition (MOCVD) [11], and so on. Most ZnO films reported have been deposited on sapphire substrates, which are not a preferable one to optoelectronic devices due to its high resistivity and price. Compared with sapphire, silicon wafers are advantageous being the substrates. They are especially suitable for ZnO growth, because the thermal expansion coefficient of Si (3.7×10−6/°C) [12] is nearly equal to that of ZnO (4×10−6/°C) [13]. The lattice mismatch between Si and ZnO is large. A buffer layer is usually needed to relieve it.

It is known that ion beam irradiation during thin film deposition can modify the properties of films, physically and chemically, and it offers the possibility to control crystal orientation, composition, lattice parameter and grain size. Therefore, the ion-beam enhanced deposition (IBED) method is expected to be one of best methods that can produce high-quality films. In this paper, we report the structural, optical and electrical properties of In–N doped ZnO films prepared by IBED method.

Section snippets

Experiments

ZnO powder (99.9% in purity) mixed with 2 atm% In2O3 (99.9% purity) powder was pressed as the sputtering target. Before the deposition, the substrates were irradiated by argon for 15 min to clean its surface. Subsequently, In-doped ZnO powder target was sputtered by Ar+ ions with energy of 1.7 KeV. N+/Ar+ (10/1) mixed ions beam extracted from the ion source with energy of 40 KeV and a beam current of 4 mA was vertically implanted into the deposited ZnO films. The direction of sputtering beam was

Structure and surface morphology

Fig. 1 shows the XRD spectrum of N–In codoped ZnO films deposited on Si substrates annealed in N2 at different temperatures for 5 min. It can be seen that the as-deposited film and post-annealed films exhibit the preferential orientation of (0 0 2) plane. Only one peak corresponding to the (0 0 2) plane of ZnO is observed in all films. The lattice parameter d calculated from XRD data is found to be larger than the bulk value. This indicates that the films deposited by IBED method are under a

Conclusion

N–In codoped ZnO films were prepared on Si and SiO2 substrates by Ion beam enhanced deposition method. It is found that the polycrystalline N–In codoped ZnO films deposited on Si and SiO2 substrates have a preferred (0 0 2) orientation, smooth surface, compact density and well adhered to the substrates. The transmittance of N–In codoped ZnO thin films on the glass substrate are about 80% in the visible range. The N–In codoped ZnO films exhibit an absorption edge of about 345 nm, which corresponds

References (16)

  • K. Ramamoorthy et al.

    Curr. Appl. Phys.

    (2004)
  • B.J. Jin et al.

    Thin Solid Films

    (2000)
  • S.Y. Lee et al.

    Thin Solid Films

    (2005)
  • D.-K. Hwang et al.

    J. Crystal Growth

    (2003)
  • Kh.A. Abdullin et al.

    Mater. Sci. Eng. B

    (2004)
  • Z.-Z. Ye et al.

    J. Crystal Growth

    (2003)
  • W. Xu et al.

    J. Crystal Growth

    (2004)
  • B.J. Zhao et al.

    J. Crystal Growth

    (2003)
There are more references available in the full text version of this article.

Cited by (25)

  • P-type single-crystalline ZnO films obtained by (Na,N) dual implantation through dynamic annealing process

    2018, Journal of Crystal Growth
    Citation Excerpt :

    It is difficult to observe skew-Gaussian profile of N concentration, which attributes to the lower ionization rate of nitrogen compared to sodium. Annealing made some implanted N ions escape from the ZnO films and some implanted N ions formed little amount of impurities like NH2– and so on [39]. Due to this reason, there have been difference between prediction and experimental results.

  • Investigation on optoelectronic performances of Al, N codoped ZnO: First-principles method

    2015, Ceramics International
    Citation Excerpt :

    As a novel third generation wide-band semiconductor material, ZnO has widely application in the field of optics, electricity, gas sensitive, ferromagnetic and photosensitive devices [1–29].

  • High mobility formation of p-type Al doped ZnO:N films annealed under NH<inf>3</inf> ambient

    2013, Journal of Physics and Chemistry of Solids
    Citation Excerpt :

    The N related acceptors are efficiently activated in 2 mol% of Al doped ZnO:N films while the excess N are removed from the co-doped films. The activated N may be in majority as compared to the donors in the co-doped films [32]. The co-doped film exhibited a higher hole concentration in the order of 6.083×1017 cm−3 and a low resistivity of 5.162×10−2 Ω cm which are far better than those reported in Table 2.

  • Thickness effect on the evolution of morphology and optical properties of ZnO films

    2011, Applied Surface Science
    Citation Excerpt :

    The electrical properties of ZnO films are extremely sensitive to substrate temperature and p type ZnO can only be obtained in a narrow range of substrate temperature [11,12]. Moreover, researches [13,14] show that annealing temperature and type of substrates also play an important role in the preparation of p type ZnO. While researchers focus on growth conditions, including deposition temperature, type of substrates and annealing temperature, investigations in the influence of thickness on the preparation of N–Al co-doped ZnO films are still not enough.

  • Growth of p-type ZnO thin film on n-type silicon substrate and its application as hybrid homojunction

    2011, Current Applied Physics
    Citation Excerpt :

    It is believed that there is excess nitrogen in the film during the film deposition and some of nitrogen replaces oxygen in the ZnO and some goes to the interstitial position inside the film. When the films annealed in Ar ambient, surplus nitrogen begins to escape from the film and the (002) peak position move toward the higher diffraction angle and reaches to the bulk ZnO, indicating stress relaxation [14]. The chemical states of N, O, Al and Zn in the as-grown and 500 °C annealed codoped ZnO film were examined by XPS analysis and are demonstrated in Fig. 2.

View all citing articles on Scopus
View full text