A new analytical threshold voltage model for the doped polysilicon thin-film transistors

Explicit calculation for grain boundary barrier height in polysilicon TFTs based on quasi-two-dimensional approach

“…For a positive gate bias V gs , as shown in Fig. 1, using the two dimensional Poisson's equation and applying Gauss' Second Law to a Gaussian box with height X d nearby a GB, yields [5,7] …”

“…Assuming Wðx; yÞ to be a parabolic distribution with x, and differentiating both sides of (2) with respect to y, we have [5,7] @ 2 wðyÞ…”

“…Further solutions have been derived to overcome the calculation complexity because of the introduction of a U-shaped DOS distribution. If compared to the previous models [5,7,8], the proposed scheme is significantly enhanced. Furthermore, its validity is demonstrated on comparisons with both numerical and experimental results.…”

“…However, it is confirmed by experiments [6] that the DOS exhibits exponential but not monoenergetic distribution. The model developed by Wu et al [7,8] improved the work of Lin et al and a U-shaped DOS distribution with an exponential band tail was taken into account. Nevertheless, as indicated by calculations [7,8], introducing a U-shaped DOS makes the calculation of GB barrier height become very complicated, which brings the main obstacle in modeling calculation, especially in circuit simulation.…”

“…The model developed by Wu et al [7,8] improved the work of Lin et al and a U-shaped DOS distribution with an exponential band tail was taken into account. Nevertheless, as indicated by calculations [7,8], introducing a U-shaped DOS makes the calculation of GB barrier height become very complicated, which brings the main obstacle in modeling calculation, especially in circuit simulation. Also, Wong et al [2] provided a quasi-2D conduction model for poly-Si TFTs based on the ''line'' charge of trap states, but the relationship between the gate voltage and the GB barrier was still an implicit function.…”