Performance of thin hydrogenated amorphous silicon thin-film transistors

Abstract

In this paper we have analyzed the influence of the mask channel length (L M ) on the performance of the 55‐nm‐hydrogenated amorphous silicon (a‐Si:H) thin‐film transistors(TFTs), incorporating nitrogen‐rich hydrogenated amorphous silicon nitride gate dielectric and phosphorus‐doped microcrystalline silicon (n +μc‐Si:H) source/drain (S/D) contacts. In our TFTs the n +μc‐Si:H S/D contacts have a specific contact resistance around or below 0.5 Ω cm2. We have shown that in our TFTs a field‐effect mobility and threshold voltage are dependent on L M , and this dependence is most likely due to the influence of the S/D contact series resistance on TFTs characteristics. Finally, we have demonstrated that if the mask channel length is extended by a ΔL (which is a distance from the S/D via edge at which the electron injection/collection is taking place) the field‐effect mobility and threshold voltage are independent of the channel length. In such a case μFE, V T , and ON/OFF current ratio around 0.76 cm2/V s, 2.5 V, and 107, respectively, has been obtained.