Nitrogen-doped ZnO (ZnO:N) films were prepared by remote plasma in situ atomic layer doping. X-ray photoelectron and absorption near-edge spectroscopies reveal the presence of Zn-N bond and a decrease in strength of the O 2p hybridized with Zn 4s states, which are consistent with the decrease of electron concentration in ZnO:N films with increasing nitrogen content and indicate the formation of acceptor states by occupation of oxygen sites with nitrogen. Linear dependence between the nitrogen content and the atomic layer doping percentage indicates the electrical properties and local electronic structures can be precisely controlled using this atomic layer doping technique.

Remote plasma in situ atomic layer doping technique was applied to prepare an n-type nitrogen-doped ZnO (n-ZnO:N) layer upon p-type magnesium-doped GaN (p-GaN:Mg) to fabricate the n-ZnO:N/p-GaN:Mg heterojuntion light-emitting diodes. The room-temperature electroluminescence exhibits a dominant ultraviolet peak at λ ≈ 370 nm from ZnO band-edge emission and suppressed luminescence from GaN, as a result of the decrease in electron concentration in ZnO and reduced electron injection from n-ZnO:N to p-GaN:Mg because of the nitrogen incorporation. The result indicates that the in situ atomic layer doping technique is an effective approach to tailoring the electrical properties of materials in device applications.

P-type phosphorus-doped ZnO (ZnO:P) films were fabricated by atomic layer deposition of ZnO upon the amorphous silica substrates, which were prepared by coating the spin-on dopant consisted of P 2 O 5 and SiO 2 on silicon wafers. Post-deposition thermal treatments were carried out to diffuse the phosphorus dopants into ZnO and to activate the phosphorus-related acceptor states. The ZnO:P films exhibited p-type conductivity with an average hole concentration of 1.05 Â 10 17 cm À3 . Significant spectral peaks associated with the acceptor states appeared in the low-temperature photoluminescence spectra of the p-type ZnO:P films. Optically-pumped stimulated emission around 393 nm was observed at room temperature, thereby indicating a good optical quality of the p-type ZnO:P film.Zinc oxide (ZnO) is a promising material for ultraviolet (UV) light-emitting diodes (LEDs) and laser diodes because of its direct band gap ($3.37 eV) and large excitonic binding energy up to 60 meV. 1-12 ZnO also has many benefits, for instance, compatibility with conventional wet chemical etching, low material cost, long-term stability, low environmental impact, and excellent radiation resistance. Several papers have reported the preparation of high-quality ZnO films using molecular beam epitaxy (MBE), 1-3 metal-organic chemical vapor deposition, 4,5 hybrid beam deposition, 6 chemical vapor deposition, 7,8 pulsed laser deposition (PLD), 9,10 and filtered cathodic vacuum arc technique. 11,12 Atomic layer deposition (ALD) is an alternative and potential technique to grow high-quality ZnO films. 13-15 It is a surface-controlled process of depositing materials with atomic-layer accuracy. Each precursor is alternately introduced into the chamber and the chemical reactions proceed at the substrate surface, leading to self-limiting and layer-by-layer growth. Hence ALD has many advantages over other techniques, including easy and accurate thickness control, conformal step coverage, high uniformity over a large area, low defect density, low deposition temperatures, and good reproducibility. 13,14 High-quality n-type ZnO films grown by ALD on c-sapphire substrates and treated by post-deposition annealing were demonstrated in our previous study. 16 The threshold intensity of stimulated emission in the n-ZnO films was as low as 35.1 kW/cm 2 , primarily ascribed to the high crystalline of the ZnO films grown by ALD.Although ZnO has a drawback of difficulty in preparing highquality and reliable p-type films, several groups have reported the growth of p-type phosphorus-doped ZnO (ZnO:P) films using MBE, 17 PLD,18, In our understanding, there is still no report on the p-type ZnO films grown upon amorphous substrates, since the well-crystallized films could not be expected because of the lack of epitaxy of ZnO on amorphous substrates. Recently, we have demonstrated highly c-axis oriented ZnO films, accompanied by the onset of optically-pumped stimulated emission, grown on amorphous glass substrates by the ALD technique. 21 In the present paper, we demonstrat...

Magnesium zinc oxide (MgxZn1−xO) thin films with tunable optical and structural properties have been prepared by in-situ atomic layer doping technique. The linear dependence of the Mg content on the Mg atomic layer doping percentage indicates this in-situ atomic layer doping is a precisely controlled technique for the Mg incorporation into ZnO. X-ray characterization reveals that solubility limit of MgO in the MgxZn1−xO films is approximately x = 0.1. Photoluminescence (PL) measurement shows the near-band-edge emission of MgxZn1−xO films shifts from 378 nm to 346 nm with an increase of the Mg content. The temperature dependent PL spectroscopy shows that the activation energy of thermal quenching process increases from 17 meV in pure ZnO to 48 meV in Mg0.1Zn0.9O films, indicating that thermal quenching is suppressed by the Mg incorporation. The optically-pumped stimulated emission at λ ∼ 356 nm was observed from the Mg0.1Zn0.9O film, manifesting the high optical quality of the MgxZn1−xO films grown by the in-situ atomic layer doping technique.

Remote plasma in-situ atomic layer doping technique was used to tailor the p-type conductivity of nitrogen and gallium co-doped MgZnO thin films. The nitrogen doping into ZnO converts the conductivity from n-type to p-type, deduced from the formation of nitrogen-related acceptors. The hole concentration increases with the incorporation of gallium, ascribed to the stabilized substitution of nitrogen at appropriate lattice sites. The stability of p-type conductivity was further improved by incorporating Mg due to the increase in solubility of nitrogen-related acceptors. Secondary ion mass spectrometry indicates the post-deposition annealing results in the removal of hydrogen, also enhancing the p-type conductivity.