Effect of water in ambient air on hysteresis in pentacene field-effect transistors containing gate dielectrics coated with polymers with different functional groups

Effect of the hydrophobicity and thickness of polymer gate dielectrics on the hysteresis behavior of pentacene-based field-effect transistors

“…[15][16][17][18] Further, water molecules in the air could create hysteresis-causing charge traps at the semiconductor/dielectric interface. [19][20][21][22] According to our previous report, 22 water adsorption into the interface between the pentacene and the polymer gate dielectric was driven by the polarity of the polymer surface, which resulted in the trap formation being able to cause hysteresis. The observed hysteresis could be explained in terms of hole and electron trap formations in accordance with the functional groups at the polymer surface.…”

“…[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] Gu et al 15,16 found that in the case of pentacene-based OFETs containing octadecyltrichlorosilanemodified SiO 2 gate dielectrics, the hysteresis observed during the full swing of a gate is due to long-lived charge traps present at the interface between semiconductor and gate dielectric, where trapping and detrapping of holes and electrons take place under an applied gate bias. [15][16][17][18] Further, water molecules in the air could create hysteresis-causing charge traps at the semiconductor/dielectric interface.…”

“…[23][24][25][26][27][28][29][30] When a polymer is used as the gate dielectric in an OFET, the end functionalities present both at the polymer surface and in the bulk have an important influence on the device performance ͑e.g., drain current, mobility, threshold voltage, and hysteresis͒. 7,31-33 Although polar functionalities, such as hydroxyl groups, are known to seriously affect the hysteresis observed during the operation of polymer-dielectric-based OFETs, 17,18,[22][23][24][25]28,29 there are only a few research papers that discuss in detail how each constituent of the polymer gate dielectric contributes to the origin and mechanism of the hysteresis.…”

Study on post-deposition annealing influenced contribution of hole and electron trapping to threshold voltage stability in organic field effect transistors

“…It is well known that silanol groups on the surface of SiO 2 can act as traps causing hysteresis [4,16]. It is also suggested in the literature that oxygen and water molecules from ambient can diffuse through the film to the dielectric/semiconductor interface and cause hysteresis [11,12]. An earlier report on the effect of post-deposition annealing on pentacene based transistors showed improvement in stability after annealing [2] where the devices were covered with an encapsulation layer in inert atmosphere before exposure to atmosphere, thereby preventing water molecules and oxygen from diffusing into the film.…”

“…We have concluded in that study that hole trapping is mainly decided by grain boundary density, while electron trapping predominantly occurs at dielectric/semiconductor interface though it can partly occur at the grain boundaries also. It is well discussed in the literature that oxygen or moisture from ambient diffusing into the interface aggravates charge trapping [11,12]. Since the present study is carried out in air and there is change in morphology and grain boundary density with annealing, apart from studying threshold voltage instability, it is also essential to determine how hole and electron traps get influenced by the above mentioned factors after annealing.…”