R. Amiruddin

Investigation on P-N dual acceptor doped p-type ZnO thin films and subsequent growth of pencil-like nanowires

Phosphorous and nitrogen dual acceptor doped p-type ZnO (PNZO) have been deposited by spray pyrolysis method on glass substrates. An equimolar doping concentration of P and N were varied from 0.25?1.25 at% with a step of 0.25 at%. Preferred orientation along (002) planes with hexagonal wurzite structure was observed from structural analysis. Morphological analysis reveals uniform distributions of grains. Electrical studies showed dual acceptor doping of P and N in ZnO results in p-type behavior. The optimum doping concentration of P and N was found to be 0.75 at% which exhibited hole concentration of 4.48???1018 cm?3 and low resistivity value of 9.6 ?.cm. Photoluminescence (PL) studies revealed that, as-deposited films exhibit strong UV emission at 383 nm of the spectrum. The surface morphology of the optimum PNZO (0.75 at%) samples were further modified in the form of vertically aligned pencil-like nanowires by modified aqueous chemical growth (ACG) process. During ACG process, more acceptor related defects such as oxygen interstitials (Oi) were formed in the PNZO nanopencils. These acceptor defects induce enhanced emission in the visible region (400 nm to 700 nm) and also promote stable p-type characteristics.

Growth and characterization of near white light emitting Al-Ga:ZnO nanowires

Aluminum and gallium dual doped ZnO (AGZO) thin film seed layers are deposited by doping equal concentration of Al and Ga ranging from 0.5–1.0 at% with a step of 0.1 at%. Structural analysis reveals hexagonal wurtzite structure of the AGZO films with a preferential orientation along (002) plane. Morphological analysis shows uniform distribution of crystallites. An average of 80% optical transmittance is observed for AGZO seed layers. The optimum doping concentration is found to be 0.8:0.8 at% of Al:Ga, which exhibits higher electron carrier concentration of 5.83 × 1020 cm−3 and lowest resistivity value of 1.72 × 10−2 Ω cm. The as-deposited conducting AGZO seed layers are eventually treated with an aqueous chemical growth (ACG) process with varying time duration, such as 5, 10 and 15 h in order to obtain one dimensional nanostructures. Morphological analysis shows that the as-grown nanowires are vertically aligned with higher growth density. Enhanced near white light emission has been observed for the as-grown AGZO nanowires with an increase in ACG process duration.

Dual acceptor doping and aging effect of p-ZnO:(Na, N) nanorod thin films by spray pyrolysis

An attempt has been made to realize p-type ZnO by dual acceptor doping (Na-N) into ZnO thin films. Na and N doped ZnO thin films of different concentrations (0 to 8 at.%) have been grown by spray pyrolysis at 623 K. The grown films on glass substrate have been characterized by X-ray diffraction (XRD), Hall measurement, UV-Vis spectrophotometer, Photoluminescence (PL) and Energy dispersive spectroscopy (EDS) to validate the p-type conduction. The surface morphology and roughness of the ZnO:(Na, N) films are studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. Hall measurement shows that all the films exhibit p-type conductivity except for 0 at.% Na-N doped ZnO film. The obtained resistivity (5.60×10−2 Ω cm) and hole concentration (3.15×1018 cm−3) for the best dual acceptor doped film is 6 at.%. It has been predicted that (NaZn−NO) acceptor complex is responsible for the p-type conduction. The p-type conductivity of the ZnO:(Na, N) films is stable even after 6 month...

Aging and annealing effects on properties of Ag-N dual-acceptor doped ZnO thin films

Ag-N dual acceptor doping into ZnO has been proposed to realize p-ZnO thin film of different concentrations (1, 2 and 4 at.%) by spray pyrolysis at 623 K and then 4 at.% films annealed at 673 K and 723 K for 1 hr. X-ray diffraction studies reveal that all the films are preferentially oriented along (002) plane. Energy dispersive spectroscopy (EDS) confirms the presence of Ag and N in 2 at.% ZnO:(Ag, N) film. Hall measurement shows that 4 at.% ZnO:(Ag, N) film achieved minimum resistivity with high hole concentration. The p-type conductivity of the ZnO:(Ag, N) films is retained even after 180 days. Photoluminescence (PL) spectra of ZnO:(Ag, N) films show low density of native defects.

Realization of highly transparent conducting CdO thin films by R.F. Magnetron sputtering for optoelectronic applications

Cadmium Oxide (CdO) thin films with low electrical resistivity and higher transparency has been deposited by r.f. magnetron sputtering on glass substrates. Sputtering process was carried out at r.f. power of 40W and with varying substrate temperatures. The structural, morphological, electrical and optical properties of the deposited films are investigated. The structral properties reveals that the as-deposited CdO films shows preferential orientation along (111) plane exhibiting face centered cubic structure. The surface morphology shows that all the films possess well defined grain boundaries with high uniformity. CdO samples deposited at substrate temperature of 150°C with r.f. power of 40W exhibits above 95% transparency in the visible region with lower electrical resistivity value in the order of 10-4 Ω.cm. The comparatevely high value of the figure of merit for the optimum sample of CdO deposited at 150°C indicates that these films are suitable for optoelectronic device applications.