Room-temperature remote-plasma sputtering of <i>c</i>-axis oriented zinc oxide thin films

Garcia‐Gancedo, Luis; Pedrós, J.; Zhu, Zhigang; Flewitt, Andrew J.; Milne, W. I.; Luo, Jikui; Ford, Chris

doi:10.1063/1.4736541

Cited by 35 publications

(27 citation statements)

References 40 publications

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“…The root mean square (rms) surface roughness is compared in Figure 5(c), showing $4 nm for ZnO and $1.5 nm for ZTO films. Previous reported values of rms surface roughness for sputtered ZnO are $2 nm, 52,53 which are in the same range. The values of rms surface roughness for ZTO are much smaller due to their amorphous nature and are comparable to previously reported values.…”

Section: -4supporting

confidence: 63%

Optimisation of amorphous zinc tin oxide thin film transistors by remote-plasma reactive sputtering

Niang

Cho

Heffernan

et al. 2016

Journal of Applied Physics

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The influence of the stoichiometry of amorphous zinc tin oxide (a-ZTO) thin films used as the semiconducting channel in thin film transistors (TFTs) is investigated. A-ZTO has been deposited using remote-plasma reactive sputtering from zinc:tin metal alloy targets with 10%, 33%, and 50% Sn at. %. Optimisations of thin films are performed by varying the oxygen flow, which is used as the reactive gas. The structural, optical, and electrical properties are investigated for the optimised films, which, after a post-deposition annealing at 500 °C in air, are also incorporated as the channel layer in TFTs. The optical band gap of a-ZTO films slightly increases from 3.5 to 3.8 eV with increasing tin content, with an average transmission ∼90% in the visible range. The surface roughness and crystallographic properties of the films are very similar before and after annealing. An a-ZTO TFT produced from the 10% Sn target shows a threshold voltage of 8 V, a switching ratio of 108, a sub-threshold slope of 0.55 V dec−1, and a field effect mobility of 15 cm2 V−1 s−1, which is a sharp increase from 0.8 cm2 V−1 s−1 obtained in a reference ZnO TFT. For TFTs produced from the 33% Sn target, the mobility is further increased to 21 cm2 V−1 s−1, but the sub-threshold slope is slightly deteriorated to 0.65 V dec−1. For TFTs produced from the 50% Sn target, the devices can no longer be switched off (i.e., there is no channel depletion). The effect of tin content on the TFT electrical performance is explained in the light of preferential sputtering encountered in reactive sputtering, which resulted in films sputtered from 10% and 33% Sn to be stoichiometrically close to the common Zn2SnO4 and ZnSnO3 phases.

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Section: -4supporting

confidence: 63%

Optimisation of amorphous zinc tin oxide thin film transistors by remote-plasma reactive sputtering

Niang

Cho

Heffernan

et al. 2016

Journal of Applied Physics

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“…The piezoelectric ZnO layer was reactively sputtered at room temperature in a high target utilisation sputtering (HiTUS) system [12], as shown in figure 1, which yields high quality and low stress films [6,13]. We used a 102 mm diameter 99.999% purity Zn target.…”

Section: Methodsmentioning

confidence: 99%

ZnO/AlN stacked BAW resonators with double resonance

DeMiguel-Ramos

Clément

Goicuria

et al. 2014

2014 IEEE International Ultrasonics Symposium

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We have fabricated BAW resonators with a piezoelectric bilayer that combines ZnO and AlN films. These stacked devices show two resonances that could be used to simultaneously track temperature variations and another parameter, such as loaded mass or pressure. We have assessed the crystal quality of the stacked piezoelectric films using XRD and FT-IR. The TCF of the devices has been measured in a temperature range from 25°C to 100°C. Both resonances show different TCFs, of -15.8 (ppm/°C) and -19.9 (ppm/°C), and quality factors Q over 500, which make them suitable for measurement of two parameters.

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“…Further information on the sputtering conditions and characterisation of the resulting ZnO films is reported elsewhere [18][19][20].…”

Section: Methodsmentioning

confidence: 99%

Experimental comparison of FBARs and SMRs responsitivities to mass loadings

Garcia‐Gancedo

Pedrós²,

Iborra³

et al. 2012

2012 IEEE International Ultrasonics Symposium

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-The utilisation of thin film technology to develop film bulk acoustic resonators (FBARs) and solidly mounted resonators (SMRs), offers great potential to outperform the sensitivity and minimum detection limit of gravimetric sensors. Up to now, the choice between FBARs and SMRs depends primarily on the users' ability to design and fabricate Bragg reflectors and/or membranes, because neither of these two types of resonators has been demonstrated to be superior to the other. In the work reported here, it is shown that identically designed FBARs and SMRs resonating at the same frequency exhibit different responsitivities, R m , to mass loadings, being the FBARs more responsive than the SMRs. For the specific device design and resonant frequency (~2 GHz) of the resonators presented, FBARs' mass responsitivity is ~20% greater than that of SMRs, and although this value should not be taken as universal for all possible device designs, it clearly indicates that FBAR devices should be favoured over SMRs in gravimetric sensing applications.

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Room-temperature remote-plasma sputtering of c-axis oriented zinc oxide thin films

Cited by 35 publications

References 40 publications

Optimisation of amorphous zinc tin oxide thin film transistors by remote-plasma reactive sputtering

Optimisation of amorphous zinc tin oxide thin film transistors by remote-plasma reactive sputtering

ZnO/AlN stacked BAW resonators with double resonance

Experimental comparison of FBARs and SMRs responsitivities to mass loadings

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