Vg,max-Vth: A new electrical characterization parameter reflecting the polysilicon film quality of LTPS TFTs

D.C.Mochou, F.V.Farmakis, D.N.Kouvatsos, A.T.Voutsas
2012. Microelectronic Engineering, 90, 76-78. doi: 10.1016/j.mee.2011.04.024

Abstract: Utilizing both of the most typical theories for the polysilicon trap energy (monoenergetic traps and traps distributed within the band gap), we prove theoretically that the difference Vg,max − Vth is an electrical parameter reflecting the polysilicon trap density. Through experimental data we verify that this parameter is related differently to the polysilicon nature than other known electrical parameters (Vth, Gm,max), thus providing new information about the film traps. Therefore, with this parameter, we suggest an easy, experimental way to directly evaluate the polysilicon film quality, unavailable till now with the already used parameters.
Graphical Abstract:

Keywords: Polysilicon gate voltage parameters, LTPS TFT, Polysilicon quality, Trap density