Volume 96, Issue 10, 15 November 2004
Index of content:
- DEVICE PHYSICS (PACS 85)
96(2004); http://dx.doi.org/10.1063/1.1798401View Description Hide Description
In this paper, we report on flexible, high capacitance, pentacene, and regioregular poly(3-hexylthiophene) (rr-P3HT) organic field-effect transistors fabricated on metallized Mylar films. The gate insulator,, was prepared by means of anodization. We show that covering the anodized gate insulator with an octadecyltrichlorosilane self-assembled monolayer or apoly(-methylstyrene) capping layer has the same effect on carrier mobility as for thermally grown silicon oxide. In addition, temperature-dependent measurements of mobility were performed on transistors fabricated with and without modification of the gate dielectric. In the case of both the pentacene and the rr-P3HT transistors, the behavior shows that the cause of the mobility enhancement through surface modification is not a reduction in the level of energetic disorder ( in Bässler’s model), as in the case of the fully amorphous organic semiconductor poly(triarylamine) [Veres et al., Adv. Funct. Mater.13, 199 (2003)]. It appears that the surface modification improves mobility by changing the morphology of the semiconducting films.
Improved contact resistance and linearity in optoelectronic devices with an intermediate quaternary layer96(2004); http://dx.doi.org/10.1063/1.1801160View Description Hide Description
The importance of the heterojunction between the contact and cladding layers in the contact resistance of optoelectronic devices is investigated. The incorporation of a quaternary layer, intermediate in composition, between these layers is shown to provide specific contact resistances at least 60% lower with some values and high-speed tandem modulators with an improved linearity and reduced series resistance. The lowering of the potential barrier for hole transport is most likely responsible for these observations. The thermal stability is quite good.
The effect of interlevel dielectric on the critical tensile stress to void nucleation for the reliability of Cu interconnects96(2004); http://dx.doi.org/10.1063/1.1787139View Description Hide Description
We have conducted electromigrationexperiments and modeling on Cu Damascene structures surrounded by different interlevel dielectric ILD and Cu-cap materials. We have determined the mechanical properties of the surrounding ILD and Cu cap to play a key role in the critical stress change to void nucleation, which is one of the critical parameters in determining electromigration lifetime or any other void-limited lifetime. Specifically, we found that decreases as the Young’s modulus of the interlevel dielectric decreases, which is the case with low-materials. In order to compensate for the lower threshold to void nucleation in low-materials, a stronger emphasis needs to be placed on the quality or adhesion of the Cu∕cap interface, which is currently the preferred site for void nucleation, so that interconnects fabricated in low-materials continue to meet the ever-increasing electromigration reliability requirements. Finally, the methodology developed in this study, which is based on experiment and modeling, can be used to determine , and therefore the critical product, for any combination of ILD and Cu-cap materials.