Thin active layer a-Si:H thin-film transistors

Influence of the semiconductor thickness on the electrical properties of transparent TFTs based on indium zinc oxide

“…However, the opposite behavior is verified, what presumably can be attributed to the shorter source-drain path formed as d s is decreased. In fact, if we assume a channel thickness of about 10 nm [13], in the 15 nm film, the electrons would pass from the source to the drain electrode almost avoiding completely the much higher resistivity of the bulk of the semiconductor [13,14]. Apart from that, and in spite of the movement of carriers in thinner films being made closer to the front surface of the semiconductor, so more influenced by the trap and defect scattering associated with the IZO/ATO interface [11], the higher number of charges of the thicker films and consequently the higher number of positively charged ions formed can contribute to an increase of the scattering phenomena and so to a degradation of the mobility as d s increases.…”

Enhanced electrical stability of nitrate ligand-based hexaaqua complexes solution-processed ultrathin a-IGZO transistors

“…Since the effective channel is formed near the IGZO/SiO 2 interface irrespective of the thickness of the film, the thicker film results in an increase in the bulk resistance. Electrons are likely to avoid the high resistivity of the bulk of the channel when they move from the source to the drain [22,23]. Therefore, in the case of our solution-processed TFTs, we assumed that the effective channel thickness was not greater than 4 nm.…”

High mobility tri-layer a-Si:H thin-film transistors with ultrathin active layer

“…In addition, the saturation mobilities for ultrathin i-layer devices are also improved over those of thicker devices. Though contact region 2-D field effects can degrade saturation region currents as active layer thickness is reduced below about 50 nm [3], for sufficiently thin active layers, these contact effects can be prevented as direct tunneling between the contacts and the channel reduces the 2-D field effects [3]. For ultrathin a-Si:H TFT's, where the thickness of the active layer is similar to the electron accumulation channel [8], both linear and saturation region characteristics can be improved over thicker a-Si:H TFT's.…”

“…Our previously reported modeling and experimental work [3] shows that decreasing active layer thickness can improve the linear region characteristics of a-Si:H TFT's. Also, observed saturation region degradation for decreasing a-Si:H thickness [4], [5] can be directly related to two-dimensional (2-D) field effects inherent to the staggered-inverted structure typically used for a-Si:H AMLCD TFT's [6].…”

“…Since AMLCD TFT's typically never operate in saturation, thin active layer a-Si:H TFT's with improved linear characteristics are preferable for display applications over thicker TFT's with better saturation characteristics. In addition, a-Si:H TFT's with very thin ( 20 nm) active layers [7] saturation currents since direct tunneling from the contacts to the gate-accumulated channel reduces the 2-D field effects [3].…”