SAM gate dielectrics

The insulating properties of the PhO-OTS layers were tested in capacitor devices. Figure 6.14 shows the breakdown characteristics of the PhO-OTS SAM gate dielectric, determined on twenty Si-SAM-Au capacitors measured on structures with a... 

Surface treatment has also been used to modify the threshold voltage as well as measured mobility in pentacene and Cgo TFTs [60]. These transistors have a heavily doped silicon/silicon oxide gate dielectric structure where alkyl, aUcylamine, and fluoroalkyl silanes are used to modify the Si02. Evaporated pentacene and Cgo form the active p- and n-type semiconductors. The experimental effect of these monolayer treatments is to alter Vj and effective mobility dramatically (see Table 3.2.3). For pentacene, the mobility decreases from -F, -CH3, untreated, -NH2, with a similar shift in Vj from 17 to -11V. The opposite trend is observed for Cgo, in which mobility is largest for the untreated material and smallest for the fluorinated SAM. In the case of Vji the alkylamine SAM shows the lowest VjOi 5.3 V. The underlying reasons for these trends are not completely understood. What is intriguing is how dramatic... 

Fig. 5.7. (a) shows the QSCV of a pentacene OFET doped using a surface dipole method [68]. (b) shows the stationary and mobile charges involved in the process. The same general principle also applies to the use of electronegative/electropositive silanes and other SAMs on gate dielectric layers for manipulating the threshold voltage. 

Majewski et al. have looked at ultrathin Si02 on metallized (aluminum metal) Mylar [32], These systems involve 60-nm aluminum on Mylar as the gate electrode, with Si02 3.5 mn ( three times the limit predicted by theory and experiments on Si02/Si). In these ultrathin Si02 dielectrics, capacitances as high as 1 TF/cm are achieved. Addition of an OTS (octyltrichlorosilane) SAM to this system reduces the... 

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