p-Type Electrical Conduction in ZnO Thin Films by Ga and N Codoping (original) (raw)
Related papers
Journal of Crystal Growth, 2013
The authors report on the p-type conductivity in the ZnO films, grown on c-Al 2 O 3 substrates by molecular-beam epitaxy, using N and Te codoping and thermal annealing. In the electrical properties, the N and Te codoping effectively suppresses the background electron concentration of ZnO films, and the thermal annealing causes the conductivity conversion from n-type to p-type. In the structural properties, the N and Te codoping deteriorates the crystalline quality of ZnO films, even if Te doping contributes to improve the crystallinity, and the thermal annealing recovers the degraded crystalline quality again. In the optical properties, the N and Te codoping simultaneously increases the donorrelated emission, the acceptor-related emission, and the nonradiative recombination in ZnO films, while the thermal annealing relatively enhances the acceptor-related emission. It is proposed that (i) the N and Te codoping simultaneously induces N-related defects and donor-type defects along with free acceptors in the ZnO films, but the amount the N-related defects is larger than the donor-type defects and the free acceptors; and (ii) the thermal annealing relatively activates the N-related defects and suppresses the donor-type defects.
Alternative sources of p-type conduction in acceptor-doped ZnO
2010
We report first-principles calculations and interface simulations for Zn 3 P 2 , a compound that may form during doping of ZnO with phosphorous. While P is a deep acceptor in ZnO and thus unable to produce p-type conductivity, we show that hole accumulation can occur at ZnO/ Zn 3 P 2 interfaces due to the unusual valence-band alignment between the two materials. This provides an explanation for the hole conductivity that has been observed in Hall measurements on phosphorous-doped ZnO.
Fabrication and characterization of P–N dual acceptor doped p-type ZnO thin films
Applied Surface Science, 2013
P and N dual-acceptor doped p-type zinc oxide (ZnO:(P, N)) films have been realized by radio frequency (rf) magnetron sputtering and post-annealing techniques. The X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS), X-ray photoelectron spectroscopy (XPS) and the Hall measurement techniques were employed to investigate the structural and the electrical properties in detail. Results indicated the electrical properties of the ZnO:(P, N) films were extremely sensitive to the annealing temperature and the conduction type could be changed dramatically from n-type to p-type, and finally changed to weak p-type in a range from 650 • C to 850 • C. The p-type ZnO:(P, N) film with the lower resistivity of 3.98 cm, a hole concentration and Hall mobility of 1.16 × 10 18 cm −3 and 1.35 cm 2 /Vs, respectively, was obtained at an optimal annealing temperature of 800 • C. The p-type conduction behavior of the ZnO:(P, N) film was confirmed by the rectifying I-V characteristics of the p-ZnO:(P, N)/n-ZnO homojunction. The chemical bonding states of P and N doped in ZnO:(P, N) film were examined by XPS analysis.
p-type conducting ZnO: fabrication and characterisation
physica status solidi (c), 2005
PACS 73.61.Ga, We report on the fabrication of ZnO:N by thermal oxidation of sputter-deposited zinc nitride. Through optimising several technological steps we achieved p-type conductivity with carrier concentration in mid 10 17 cm -3 range and mobility of ~10 cm 2 /Vs. PL spectra of p-type ZnO:N films show a sharp peak at 3.36 eV, most likely due to neutral acceptor bound excitons. The transmittance of p-ZnO:N in the whole visible spectrum is ~ 80 % making it suitable for transparent electronics.
Realization of p-Type Conductivity in ZnO via Potassium Doping
Acta Physica Polonica A, 2016
Our work focuses on the study of the electronic structure of undoped and K-doped ZnO using density functional theory as implemented in the Wien2k package. Generalized gradient approximation and GGA plus Tran-Blahamodified Becke-Johnson (TB-mBJ) were used to calculate the exchange-correlation energy. From the electronic properties, ZnO has a direct band gap in (Γ − Γ) direction with a value of 0.76 eV within GGA and 2.63 eV within GGA + TB-mBJ. For the K-doped ZnO (12.5%) the gap was found to be 1.15 eV within GGA and 3.28 eV within GGA + TB-mBJ, we have observed that an emersion of a new narrow band exists in the valence band which is mainly caused by K 3p states with a little Zn 4s and Zn 3d effect.
Conversion of n-type to p-type conductivity in ZnO by incorporation of Ag and Ag-Li
Elemental doping is an efficient strategy to modulate different properties of semiconductors. Conversion from ntype to p-type and band gap modulation of ZnO are investigated by theoretical and experimental pathways studies. The structural, electronic and optical properties of undoped, Ag and Ag-Li doped ZnO are studied in the framework of density functional theory (DFT). The value of direct band gap is found to be ~ 0.730, 0.440, 0.274, and 0.870 eV for undoped, Ag = 6.25% and 12.5% doped, and Ag= 6.25, Li= 6.25% co-doped ZnO, respectively. Acceptor levels are created at the top of the valence band and above the Fermi level in Ag and Ag-Li doped ZnO which reveals that Ag and Ag-Li are promising dopants for generating p-type ZnO. Importantly, a remarkable change in photoconductivity and optical properties are observed. The surface morphology of the spray deposited Zn 100-x Ag x O (x = 0.0-20%) and Zn 100-x-y Ag x Li y O (x = 5, y = 0.0-10%) thin films are changed with Ag and Ag-Li contents. The XRD patterns confirmed the hexagonal structure of all the deposited films. The band gap decreases from 3.27 to 3.08 eV (for Ag doped ZnO) and increases from 3.16 to 3.38 eV for Ag-Li doping ZnO, respectively. The dielectric constants and photoconductivity spectra support the formation of p-type conductivity of Zn 100x Ag x O and Zn 100-x-y Ag x Li y O, which are in good agreement with the available theoretical and experimental reports. Thus, the studies performed in this work help us to understand the Ag and Ag-Li doping mechanism in ZnO; opening up possible directions toward the fabrication of p-type ZnO for advanced electronic and optoelectronic applications.
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.
Fabrication of the low-resistive p-type ZnO by codoping method
Physica B: Condensed Matter, 2001
We have demonstrated the possibility of growing p-type ZnO films by a pulsed laser deposition technique combined with plasma gas source. The p-type ZnO film has been fabricated by passing N 2 O gas through an electron cyclotron resonance (ECR) or RF plasma source. N 2 O gas is effective to prevent ''O'' vacancy from occurring and introduce ''N'' as an acceptor, at the same time. With Ga and N codoping technique, we have observed a room temperature resistivity of 0.5 O cm and a carrier concentration of 5 Â 10 19 cm À3 in ZnO film on glass substrate. Two-step growth, with a thin ZnO template layer formed at high temperature, is quite effective to realize a well crystallized growth at low temperature. The observed p-type ZnO films will open the door for practical applications in various oxide electronic devices.
Induction of p-type conduction in sputtered deposited Al-N codoped ZnO thin films
Optics Communications, 2010
Al and N codoped ZnO thin films were grown on n-Si (100) substrate by sputtering technique. Hall effect measurements of as-grown films exhibited n-type conduction, however 500°C Ar annealed codoped films showed p-type conductivity with a hole concentration of 9.9 × 10 16 cm − 3 , resistivity of 15.95 Ω-cm and hole mobility of 3.95 cm 2 /Vs, respectively. Codoped ZnO thin films were found to be highly c-axis oriented with good crystal quality. A neutral acceptor-bound exciton and donor-acceptor-pair emissions that appeared at room temperature photoluminescence measurement verify p-type conduction in Al and N codoped ZnO film. The current-voltage characteristics of p-n heterojunction evidently showed a diode like rectifying behaviour.
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.