ZnO-Based Thin Film Transistor Fabricated Using Radio Frequency Magnetron Sputtering at Low Temperature

Abstract

Thin film transistors (TFTs) were fabricated on a glass substrate using zinc oxide material as a channel layer. The layers were grown by radio frequency magnetron sputtering method at a temperature of 100 C. The output characteristics of a TFT device showed that there is a reduction in drain current at increased drain-source voltage and gate-source voltage. This evidenced the existence of self-heating effect which may be due to increased donor type point defects. The electrical characteristics of a device show an improved intrinsic channel mobility of 4 cm 2 /Vs, threshold voltage of 12 V, sub-threshold swing of 1 V/decade, and very much decreased off current of the order 10 À12 A.

Reduction of self-heating effect in (Ga)ZnO thin film transistor

“…No intermediate phase formation was observed confirming the high purity of the film. SEM and XRD results revealed the surface morphology of low T (Ga)ZnO film were enhanced by proper control of growth parameters during sputtering when compared with ZnO thin film grown with the same sputtering parameters as reported elsewhere [8].…”

“…The peak at 2θ = 34.3°was found to be the (0 0 2) reflection of polycrystalline (Ga)ZnO with hexagonal wurtzite structure along caxis according to the Drift model [16]. The intense and sharper peak was due to the improved polycrystallinity and larger grain size as compared to ZnO film reported elsewhere [8]. No intermediate phase formation was observed confirming the high purity of the film.…”

“…But there are meagre reports on SHE on ZnO-based TFTs. In our previous study, SHE was observed on ZnO-based TFT grown at 100°C [8]. There are no reports on reducing this heating effect occurred in the ZnO-based transistor.…”

Oxide-Based Electric-Double-Layer Thin-Film Transistors on a Flexible Substrate

“…The estimated contact resistance of the device is less than 10% of the total channel resistance, even at V G = 1 V. It is also found that I D exhibits a clear pinch off and saturates at higher V D . A slight decrease of I D is observed in the saturation regime, which might be caused by a hot carrier effect and/or selfheating effects [25][26][27][28]. Under such effects, charge trapping occurs, resulting in a positive threshold voltage shift and a slight decrease in I D .…”

Factors influencing the nanostructure of obliquely deposited thin films

“…Silica thin films have been extensively grown by the OAD technique using evaporation, but much work has not yet been done using sputtering. Sputtering is one kind of physical vapour deposition process primarily used for the deposition of a large range of materials for varied applications [7][8][9][10][11]. Some of the striking advantages of the sputtering process over evaporation are better uniformity, homogeneity and adhesion with the substrate of the deposited films.…”