Effect of annealing temperature on optical and electrical properties of nitrogen implanted p-type ZnMgO thin films

Abstract

p-type nitrogen doped Zn 1-x Mg x O (x = 0.15) thin films were prepared on n-type silicon substrates by RF sputtering. Plasma-immersion-ion technique and rapid-thermal process were used to implant nitrogen and annealing (700-1000°C) of these films respectively. Annealed samples at 700, 800, 900 and 1000°C showed effective improvement of the structural and optical properties. X-ray diffraction spectra showed improvement in \002[ orientation of films with increase in annealing temperatures. In Raman spectra, the peak at 436 cm -1 corresponds to E 2 high phonons mode of ZnMgO wurtzite structure and FWHM of this peak decreases with increase in annealing temperature, indicating improvement in crystalline quality. The scanning electron microscopy results demonstrate that nitrogen-implanted ZnMgO film annealed at 1000°C has better morphology in comparison to other films. Low-temperature (15 K) photoluminescence measurements revealed acceptorbound exciton peak at 3.45 eV and donor-bound exciton peak around 3.52 eV. Increased intensity of acceptor-bound exciton peak with increasing annealing temperature proves that nitrogen implantation and subsequent annealing increase the acceptor concentration in the film, indicating tendency for p-type conduction at higher annealing temperature. The film annealed at 1000°C was observed to produce only acceptor-bound exciton emission and no donor-bound exciton emission was occurred. Hall-effect measurements showed p-type conductivity for annealed films in temperature range at 800-1000°C. The acceptor level at 3.45 eV in PL spectra is responsible for this p-type conduction in these films. The highest hole concentration of 1.91 9 10 15 cm -3 has been achieved for film annealed at 1000°C.

Photoelectric Detectors Based on Inorganic p‐Type Semiconductor Materials

“…Considering that the bandgap of alloy semiconductor ZnMgO can be tuned by changing the concentration of Mg element, ZnMgO exhibits great potential application in optoelectronic devices, especially in deep UV photodetectors. The preparation of p‐type ZnMgO is a hot topic in related fields, and group I and V elements are considered as suitable acceptors for achieving the fabrication of p‐type ZnMgO . Niobium‐doped MoS 2 , gold NP modified graphene, and benzyl viologen (BV)‐ modified black phosphorus (BP) have been obtained and characterized as p‐type semiconductors.…”

Vapor-Transport Synthesis and Annealing Study of ZnxMg1–xO Nanowire Arrays for Selective, Solar-Blind UV-C Detection

“…Principally, the combined effect of a smaller electronegativity and electronic radius of Mg 2+ (Pauling electronegativity: 1.31 and 0.57 Å radius) to that of Zn 2+ (Pauling electronegativity: 1.65 and 0.60 Å radius) facilitates the formation of the Mg–O bond and leads to the decrease of observed lattice parameters. 12,24−27 Thus, Mg 2+ is effectively substituting Zn 2+ without significantly modifying the ZnO nanowire crystal structure, which further explains the reduced nanowire size distributions from Figure 2c. However, when these modified lattice parameters are scaled up to the average nanowire dimensions, we find that this phenomenon alone does not completely account for the observed reduction in array aspect ratio.…”

“…As shown in Figure b,c, annealing results in a right-shift of the ZnO a axis corresponding to the (100) plane (2θ = 31.7°), as well as the ZnO c axis corresponding to the (002) plane (2θ = 34.4°), by as high as Δ2θ = 0.3° in both cases (note: the presence of bimodal peaks arises from dissimilar K α excitation energies emitted from the diffractometer). Principally, the combined effect of a smaller electronegativity and electronic radius of Mg 2+ (Pauling electronegativity: 1.31 and 0.57 Å radius) to that of Zn 2+ (Pauling electronegativity: 1.65 and 0.60 Å radius) facilitates the formation of the Mg–O bond and leads to the decrease of observed lattice parameters. ,− Thus, Mg 2+ is effectively substituting Zn 2+ without significantly modifying the ZnO nanowire crystal structure, which further explains the reduced nanowire size distributions from Figure c. However, when these modified lattice parameters are scaled up to the average nanowire dimensions, we find that this phenomenon alone does not completely account for the observed reduction in array aspect ratio.…”

The Effect of High Temperature Annealing on the Photoluminescence of ZnMgO Alloys

“…For the ZnMgO films grown by MOCVD, rapid thermal annealing in nitrogen at 800 °C resulted in the increasing of the integrated intensity of exciton PL of 31 times, while the annealing in oxygen produced its decreasing . At the same time, nitrogen‐implanted ZnMgO films produced by RF sputtering and annealed at 1000 °C in oxygen ambient demonstrated significant improvement of the structural and optical properties as compared with the as‐grown films …”

“…At present, many techniques have been employed to prepare ZnMgO films, in particular, atomic layer deposition, pulsed laser deposition (PLD), magnetron sputtering, molecular beam epitaxy, metalorganic chemical vapor deposition (MOCVD), metalorganic vapor‐phase epitaxy (MOVPE), sol–gel, etc. As a rule, the deposition methods imply additional thermal treatment which can relieve the accumulated strain energy, diminish defects and increase grain sizes, as well as stimulate Zn/Mg interdiffusion processes and affect the band‐gap of the material. The optimal annealing conditions vary for the films produced by different growth techniques.…”