Fabrication of the low-resistive p-type ZnO by codoping method (original) (raw)
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Growth of epitaxial p-type ZnO thin films by codoping of Ga and N
Applied Physics Letters, 2006
Codoping of Ga and N was utilized to realize p-type conduction in ZnO films using rf magnetron sputtering. The films obtained at 550°C on sapphire showed resistivity and hole concentrations of 38 ⍀ cm and 3.9ϫ 10 17 cm −3 , respectively. ZnO films also showed a p-type behavior on p-Si with better electrical properties. ZnO homojunctions synthesized by in situ deposition of Ga-N codoped p-ZnO layer on Ga doped n-ZnO layer showed clear p-n diode characteristics. Low temperature photoluminescence spectra of codoped films also revealed a dominant peak at 3.12 eV. The codoped films showed a dense columnar structure with a c-axis preferred orientation.
Journal of Materials Processing Technology, 2008
Zinc oxide films p-type doping Light-emitting devices a b s t r a c t N-doped ZnO films have been grown on (0 0 0 1) sapphire substrates by a novel low-pressure plasma-assisted metalorganic chemical vapor deposition system using N 2 O plasma as doping source. X-ray photoelectron spectroscopy analysis confirmed the incorporation of N into the ZnO films. Room temperature p-type conduction was achieved for the N-doped ZnO film at suitable substrate temperatures, with the resistivity of 8.71 cm, hole concentration up to 3.44 × 10 17 cm −3 and mobility of 2.09 cm 2 /V s. In the photoluminescence (PL) measurement, a strong near-band-edge emission was observed for both undoped and N-doped films, while the deep-level emission was almost undetectable, which confirmed that the obtained ZnO-based films were well close to stoichiometry and of optically high quality. (J. Bian).
Journal of Crystal Growth, 2001
P-type ZnO films with carrier density 3-6 Â 10 18 cm À3 , resistivity 2-5 O cm and Hall mobility=0.1-0.4 cm 2 V À1 s À1 have been grown on fused silica and glass substrate by pulsed laser reactive deposition using a pure metal Zn target in N 2 O plasma. The N acceptor doping was effectively enhanced using the active N formed by N 2 O gas passing through an electron resonance source during the pulsed laser reactive deposition process. P-type conduction was achieved by optimizing the microwave-input power (E) and deposition pressure (P N2O). These electrical properties are sufficient for some practical applications. We expect this result to facilitate the fabrication of transparent p-n homojunctions suitable for light-emitting diodes.
Doping of As, P and N in laser deposited ZnO films
Journal of Crystal Growth, 2006
Preparation of p-type ZnO thin films on Al 2 O 3 (0 0 0 1) substrates is reported, which involves two different p-type dopant source materials such as Zn 3 As 2 and Zn 3 P 2 for As and P doping, respectively, during pulsed laser deposition, while an ion implantation method was used to dope N in the ZnO films. The hole concentrations of 2.5 Â 10 17-1.2 Â 10 18 cm À3 have been observed in As-doped p-type ZnO films after being underwent rapid thermal annealing (RTA) at 200 1C under an N 2 ambient. In the case of P doping, 3 mol% P-doped ZnO films at RTA between 600 and 800 1C under an O 2 ambient exhibited p-type behavior with the hole concentrations of 5.1 Â 10 14-1.5 Â 10 17 cm À3. In the case of N doping, after RTA up to 700 1C, films implanted with an N dose of 1 Â 10 12 ions/cm 2 showed p-type conductivity with a hole concentration of 6.01A^1017cmAˋ3andalowresistivityof6.01 Â 10 17 cm À3 and a low resistivity of 6.01A^1017cmAˋ3andalowresistivityof5.2 Â 10 À1 O cm. The low-temperature photoluminescence results showed the peak associated with the neutral-acceptor bound exciton (A1, X) emission only in the films showing p-type behavior.
Fabrication of low resistivity p-type ZnO thin films by implanting N + ions
Transparent and conductive oxide films have been extensively researched in recent years for the breadth of their optically technological applications. The growth of high quality n-type ZnO films can be easily realized. One of the big challenges is the difficultly of achieving low resistivity p-type conduction for ZnO thin films. In this work, we prepared the p-type ZnO films by r.f. reactive magnetron sputtering following by N + ions implantation and subsequent annealing in a vacuum to achieve low resistivity conductive thin films. The structural, electrical and optical properties were examined by X-ray diffraction, UV-visible, and Hall-effect measurements. The experimental results show that the films have proud (002) preferred orientation. The second phase Zn 3 N 2 diffraction peak doesn't appear in ZnO thin films. All of the zinc oxide films show good transmittance in the range of 500-550 nm. The average transmittance in the visible spectrum can be above 80% in this study. The optical energy gap increases with increasing the amount of N + ions implanted. The maximum value of the optical energy gap gained in this study is 3.30 eV when the implanted amount of N + ions was 5×10 17 cm-2 .To study the electrical stability, the p-type ZnO films were measured again after 30 days aging at room temperature. The film still kept p-type conduction without any obvious degradation of electric conduction. The resistivity of p-type ZnO obtained in this study varied from 1.05 ×10-1 to 9.80 ×10-1 ohm-cm.
Pulsed laser deposition of Zr–N codoped p -type ZnO thin films
Applied Physics A-materials Science & Processing, 2008
Present p-type ZnO films tend to exhibit high resistivity and low carrier concentration, and they revert to their natural n-type state within days after deposition. One approach to grow higher quality p-type ZnO is by codoping the ZnO during growth. This article describes recent results from the growth and characterization of Zr–N codoped p-type ZnO thin films by pulsed laser deposition (PLD) on (0001) sapphire substrates. For this work, both N-doped and Zr–N codoped p-type ZnO films were grown for comparison purposes at substrate temperatures ranging between 400 to 700 °C and N2O background pressures between 10−5 to 10−2 Torr. The carrier type and conduction were found to be very sensitive to substrate temperature and N2O deposition pressure. P-type conduction was observed for films grown at pressures between 10−3 to 10−2 Torr. The Zr–N codoped ZnO films grown at 550 °C in 1×10−3 Torr of N2O show p-type conduction behavior with a very low resistivity of 0.89 Ω-cm, a carrier concentration of 5.0×1018 cm−3, and a Hall mobility of 1.4 cm2 V−1 s−1. The structure, morphology and optical properties were also evaluated for both N-doped and Zr–N codoped ZnO films.
Journal of Crystal Growth, 2007
In order to decrease the free-electron concentration and increase the crystalline quality, zinc oxide (ZnO) thin films were deposited on sapphire (0 0 0 1) substrates by oxygen plasma-assisted pulsed laser deposition (PLD). ZnO films showed higher oxygen composition, stronger diffraction intensity of the (0 0 0 2) direction, and larger grain size with regular hexagonal grain shape. The free-electron concentration was decreased greatly from 1019to10 19 to 1019to10 14 cm À3 and the Hall mobility was increased from 6.8 to 37 cm 2 V À1 s À1. Furthermore, the intensity of the resonant Raman scattering and ultraviolet photoluminescence emission was increased. This enhancement of the crystalline, electrical and optical quality would be attributed to the increase of high activity oxygen density introduced by the plasma oxygen source.
Growth and characterization of doped ZnO films
2007
We report here the synthesis of ZnO films by the pulsed-laser deposition technique using various novel conditions. The dopants are As, Ga, Al and N. The films show excellent crystalline quality with atomically smooth surface morphology. The electrical resistivity was found to be close to 2 x~10-4 ohm-cm and transmittance >85% with both Ga and Al doping. Doping with As shows several distinct transitions in their electrical resistivity and strong aging effects. On the other hand, doping with Mn in ZnO reduces the grain size. On the other hand, doping with trivalent Er ions in ZnO films causes two effects: for high doping (>8 wt%), a substantial enhancement of diagonal piezo-optic effect (up to 3.7*10-13 m2/N at λ=633 nm) was observed due to creation of additional dipole moments at the interface of the film and the substrate, and higher electrical conductivity with enhanced 1.54 μm emission was demonstrated at room temperature for low concentration (<2 wt%) of Er. Furthermore, no quenching effects in emission characteristics at 1.54 μm were observed up to 2 wt % of Er-doping in ZnO at room-temperature.