We report on the growth of Li-Ni codoped p-type ZnO thin films using pulsed laser deposition. Two mole percent Li monodoped ZnO film shows highly insulating behavior. However, a spectacular decrease in electrical resistivity, from 3.6 × 10 3 to 0.15 Ω cm, is observed by incorporating 2 mol % of Ni in the Lidoped ZnOfilm.Moreover, the activation energy drops to 6meV from78 meV with Ni incorporation in Li:ZnO lattice. The codoped [ZnO:(Li, Ni)] thin film shows p-type conduction with room temperature hole concentration of 3.2 × 10 17 cm -3. Photo-Hall measurements show that the Li-Ni codoped p-ZnOfilm is highly stable even with UV illumination. XPS measurements reveal that most favorable chemical state of Ni is Ni 3+ in (Li, Ni): ZnO. We argue that these Ni 3+ ions act as reactive donors and increase the Li solubility limit. Codoping of Li, with other transitional metal ions (Mn, Co, etc.) in place of Ni could be the key to realize hole-dominated conductivity in ZnO to envisage ZnO-based homoepitaxial devices. © 2011 American Chemical Society.

Mamidanna Sri Ramachandra Rao

Department Of Physics

Chemical state

Co-doped

Co-doping

Electrical resistivity

Homoepitaxial

II-VI semiconductor

MOLE PERCENT

P type ZnO thin film

P-Type conduction

Room temperature

Solubility limits

TRANSITIONAL METAL IONS

UV ILLUMINATIONS

XPS MEASUREMENTS

ZnO films

Activation energy

Deposition

electric conductivity

Hole concentration

Manganese

Metal ions

Metallic films

Pulsed laser deposition

Thin films

Vapor deposition

Zinc oxide

Semiconductor doping

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

ACS Applied Materials and Interfaces

Abstract We report on the growth of violet emitting p-type ZnO thin films, with phosphorous (P) and nitrogen (N) codoping, using pulsed laser deposition. XPS studies show that the phosphorous is substituted at Zn site, whereas nitrogen is substituted at oxygen site. Hall measurements confirmed the p-type nature in codoped ZnO thin films. I-V characteristics of the heterojunction formed by n-Si and P, N: ZnO showed rectifying nature. Strong violet emission in PL spectra is attributed to the formation of zinc vacancies. We propose a defect complex, (P Zn -V Zn -4N O ), which acts as an effective acceptor in the P and N codoped ZnO. © 2015 Elsevier B.V.

Applied Surface Science

Zn-vacancy induced violet emission in p-type phosphorus and nitrogen codoped ZnO thin films grown by pulsed laser deposition

The control of size, shape, and physical properties by surface modifications are of immense interest in materials which are of technological importance. The ZnO-based wide bandgap semiconductor nanoparticles have gained significant interest in the research community due to its large exciton binding energy (60 meV). Further substantial renewed interest in ZnO-based compounds is due to the possible realization of p-type conduction and ferromagnetic behavior when doped with transition metals. In this report we present interesting results on the ZnO nanoparticle system in which the control of dopants, morphology, and the surface modification can influence significantly the physical properties of the ZnO nanoparticles. First, we present the methods to control the morphology of the ZnO particle to obtain nanorods. As an example we show the effect of Li dopant on the morphology control of Co and Ni doped ZnO. The effect of morphology on the magnetic properties of these compounds is discussed further. We also demonstrate the effect of the n-type charge carriers on the magnetic and optical properties by doping aliovalent cations in Zn(Co)O. Following this we comment on the magnetic property manipulations by surfactant treatment of transition metal (TM) doped ZnO and defect stabilization in ZnO by Mg doping. The magnetic coupling is RKKY-like both with and without Li co-doping. Finally, we provide the significant implications of these results on the nanorods structures of room temperature ferromagnetic materials by first-principles modeling. These theoretical analyses demonstrate that Li co-doping has primarily two effects in bulk Zn1-xMxO (with M = Co or Ni). First, the Li-on-Zn acceptors increase the local magnetic moment by depopulating the M 3d minority spin-states. Second, Li-on- Zn prefer to be closer to the M atoms to compensate the M-O bonds and to locally depopulate the 3d states, and this will help in forming high aspect nanostructures. The observed room temperature ferromagnetism in Li co-doped Zn1-xMxO nanorods can therefore be explained by the better rod morphology in combination with locally ionizing the magnetic M atoms. © Springer India 2014.

Springer Series in Materials Science

Experimental and theoretical investigations of dopant, defect, and morphology control on the magnetic and optical properties of transition metal doped ZnO nanoparticles

Ni doped, Li doped and (Li, Ni) codoped ZnO thin films were successfully grown using a pulsed laser deposition technique. Undoped and doped ZnO thin films were investigated using extended x-ray absorption fine structure (EXAFS) and x-ray absorption near edge spectroscopy (XANES). Preliminary investigations on the Zn K-edge of the undoped and doped ZnO thin films revealed that doping has not influenced the average Zn-Zn bond length and Debye-Waller factor. This shows that both Ni and Li doping do not appreciably affect the average local environment of Zn. All the doped ZnO thin films exhibited more than 50% of substitutional Ni, with a maximum of 77% for 2% Ni and 2% Li doped ZnO thin film. The contribution of Ni metal to the EXAFS signal clearly reveals the presence of Ni clusters. The Ni-Ni distance in the Ni0 nanoclusters, which are formed in the film, is shorter with respect to the reference Ni metal foil and the Debye-Waller factor is higher. Both facts perfectly reflect what is expected for metal nanoparticles. At the highest doping concentration (5%), the presence of Li favors the growth of a secondary NiO phase. Indeed, 2% Ni and 5% Li doped ZnO thin film shows %Ni sub = 75 ± 11, %Ni met = 10 ± 8, %NiO = 15 ± 8. XANES studies further confirm that the substitutional Ni is more than 50% in all the samples. These results explain the observed magnetic properties. © 2013 IOP Publishing Ltd.

Journal of Physics Condensed Matter

EXAFS and XANES investigation of (Li, Ni) codoped ZnO thin films grown by pulsed laser deposition

Journal of Applied Physics

Raman scattering studies of p-type Sb-doped ZnO thin films

Applied Physics Letters

The grain boundary related p-type conductivity in ZnO films prepared by ultrasonic spray pyrolysis

Advanced Materials

Ultralow-Threshold Laser Realized in Zinc Oxide

Reproducible growth of p-type ZnO:N using a modified atomic layer deposition process combined with dark annealing

Demonstration of a ZnO/MgZnO-based one-dimensional photonic crystal multiquantum well laser

A codoping route to realize low resistive and stable p-type conduction in (Li,Ni):ZnOThin films grownby pulsed laserdeposition

Journal	ACS Applied Materials and Interfaces
ISSN	19448244
Open Access	No