We report on the zinc oxide (ZnO) thin films obtained by the atomic layer deposition (ALD) method using diethyl zinc and water precursors, which allowed us to lower deposition temperature to below . The so-obtained “as grown” ZnO layers are polycrystalline and show excitonic photoluminescence (PL) at room temperature, even if the deposition temperature was lowered down to . Defect-related PL bands are of low intensity and are absent for layers grown at . This is evidence that extremely low temperature growth by ALD can result in high quality ZnO thin films with inefficient nonradiative decay channels and with thermodynamically blocked self-compensation processes.
22 June 2012 in Semiconductor Science and Technology
We report on zinc oxide thin films grown by atomic layer deposition at a low temperature, which is compatible with a low thermal budget required for some novel electronic devices. By selecting appropriate precursors and process parameters, we were able to obtain films with controllable electrical parameters, from heavily -type to the resistive ones. Optimization of the growth process together with the low temperature deposition led to ZnO thin films, in which no defect-related photoluminescence bands are observed. Such films show anticorrelation between mobility and free-electron concentration, which indicates that low electron concentration is a result of lower number of defects rather than the self-compensation effect.
We report on the electrical properties of thin film transistors based on zinc oxide (ZnO) layers grown by low temperature atomic layer deposition. As evidenced through Hall effect measurements, a drastic decrease of the carrier concentration occurred for ZnO films grown at . Time of flight–secondary ions mass spectroscopy analysis revealed that this decrease is associated with an increase of the hydroxide groups in the ZnO layer which suppressed oxygen vacancy formation. Transistors fabricated from ZnO films grown at exhibit a high ratio and an encouraging intrinsic channel mobility .
The electronic structure of the first Pu-based superconductor is explored using photoelectron spectroscopy and a novel theoretical scheme. Exceptional agreement between calculation and experiment defines a path forward for understanding the electronic structure aspects of Pu-based materials. The photoemission results show two separate regions of electron spectral intensity, one at the Fermi energy and another centered 1.2 eV below the Fermi level. The results for clearly indicate electron behavior on the threshold between localized and itinerant. Comparisons to delta phase Pu metal show a broader framework for understanding the fundamental electronic properties of the Pu levels in general within two configurations, one localized and one itinerant.
19 April 2011 in Journal of Materials Science: Materials in Electronics
We obtained zinc oxide films doped with aluminum using atomic layer deposition (ALD). Their morphology, growth mode, optical and electrical properties are studied. Al content dependence is analyzed. Carrier scattering mechanisms in ZnO:Al (AZO) films are investigated from conductivity versus temperature measurements. We also discuss how the film thickness affects its resistivity and optical transmission. The obtained film resistivities, i.e. 7 × 10−4 Ωcm, belong to the lowest reported so far for transparent ZnO:Al films grown by the ALD method.