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Abstract In metal‐oxide thin‐film transistors (TFTs), high‐kgate dielectrics often yield a higher electron mobility than SiO2. However, investigations regarding the mechanism of this high‐k“mobility boost” are relatively scarce. To explore this phenomenon, solution‐processed In2O3TFTs are fabricated using eight different gate dielectrics (SiO2, Al2O3, ZrO2, HfO2, and bilayer SiO2/high‐kstructures). With these structures, the total gate capacitance can be varied independently from the semiconductor–dielectric interface to study this mobility enhancement. It is shown that the mobility enhancement is a combination of the effects of areal gate capacitance and interface quality for disordered oxide semiconductor devices. The ZrO2‐gated TFTs achieve the highest mobility by inducing more accumulation charge with higher gate capacitance. Surprisingly, however, when the gate capacitance is held constant, no mobility enhancement is observed with the high‐kgate dielectrics compared to SiO2.
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Accurate Field‐Effect Mobility and Threshold Voltage Estimation for Thin‐Film Transistors with Gate‐Voltage‐Dependent Mobility in Linear Region
Abstract The measurement of mobility and threshold voltage in thin‐film transistors (TFTs) in which the mobility is a function of gate voltage or carrier density is usually done inaccurately. Herein, accurate mobility calculations within the framework of the gradual channel approximation are described. Conventionally, the derivative of drain current with respect to gate voltage is often used to calculate mobilities in the linear region. This procedure often leads to errors when the mobility is not constant. Using a first‐order finite difference‐based calculations, it is shown how the correct field‐effect mobility can be extracted. The corrected mobility can be smaller than the conventionally calculated field‐effect mobility by up to a factor of 2. It is also shown that the corrected field‐effect mobility is identical to the average mobility. A threshold voltage that is independent of gate voltage value and suitable for disordered semiconductors is used for more accurate mobility calculations. The mobility and threshold voltage calculations are illustrated with experimental data from multiple TFTs with indium gallium zinc oxide, zinc tin oxide, and molybdenum disulfide channel layers.
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- Award ID(s):
- 1938179
- PAR ID:
- 10396436
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Electronic Materials
- Volume:
- 9
- Issue:
- 2
- ISSN:
- 2199-160X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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