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The authors investigated the field emission from vertically well-aligned zinc oxide (ZnO) nanoneedles grown on the Au/Ti/n-Si (100) substrate using metal organic chemical vapor deposition. The turn-on field of ZnO nanoneedles was about 0.85 V/μm at the current density of 0.1 μA/cm2, and the emission current density of 1 mA/cm2 was achieved at the applied electric field of 5.0 V/μm. The low turn-on field of the ZnO nanoneedles was attributed to very sharp tip morphology, and the high emission current density was mainly caused by the formation of the stable Ohmic contact between the ZnO nanoneedles and Au film. [ABSTRACT FROM AUTHOR]

Abstract: In this work, Y2O3 was evaluated as a gate insulator for thin film transistors fabricated using an amorphous InGaZnO4 (a-IGZO) active layer. The properties of Y2O3 were examined as a function of various processing parameters including plasma power, chamber gas conditions, and working pressure. The leakage current density for the Y2O3 film prepared under the optimum conditions was observed to be ~3.5×10−9 A/cm2 at an electric field of 1 MV/cm. The RMS roughness of the Y2O3 film was improved from 1.6 nm to 0.8 nm by employing an ALD (Atomic Layer Deposition) HfO2 underlayer. Using the optimized Y2O3 deposition conditions, thin film transistors (TFTs) were fabricated on a glass substrate. The important TFT device parameters of the on/off current ratio, sub-threshold swing, threshold voltage, and electric field mobility were measured to be 7.0×107, 0.18 V/dec, 1.1 V, and 3.3 cm2/Vs, respectively. The stacked insulator consisting of Y2O3/HfO2 was highly effective in enhancing the device properties. [Copyright &y& Elsevier]

Abstract: In this study, the characteristics of positive bias temperature instability (PBTI) and cyclic constant voltage stress (CVS) in thin film transistors (TFTs) incorporating Ni-FALC poly-Si film were investigated under various stress conditions. In PBTI, the threshold voltage (V TH) was degraded by a vertical electric field on the gate stack, and an abrupt variation of V TH was attributed to the creation of defects in the gate oxide and the increase of the effective interface trap state. In contrast to the formation of defects, the poly-Si film was not sensitive to PBTI stress (the fluctuation in the grain boundary trap density was just 5.6%). In two-cycle CVS of devices before and after O2 plasma treatment, the direction of the V TH shift and polarity of bias showed good correlation. In particular, the O2 plasma-treated device demonstrated low Subthreshold swing (S.S) and low minimum drain current compared to the untreated one. The improvement of device performance seemed to originate from the reduction of effective interface trap sites and leakage current paths. [Copyright &y& Elsevier]