Field effect transistors, device characteristics

While the discussion in this chapter has focused on molecular layers on single crystal silicon surfaces, the attachment chemistries discussed here could easily be applied to functionalize silicon nanowires or nanoparticles. Silicon nanowires have been shown to exhibit interesting electrical transport characteristics and have been used to fabricate nanoscale pn junctions [95], field effect transistors [96] and biochemical sensors [97-100]. However, all these interesting phenomena have been reported on oxidized silicon nanowires. It is likely that better control over the surface properties, as could be achieved by employing some of the chemistry discussed here, could significantly improve the performance of these nanowire-based devices. From another perspective, silicon nanowires could prove extremely... 

Uemura, T. Kodzasa, N. Takada, T. Kamata, and K. Yase, Influence of moisture on device characteristics of polyfhiophene-based field-efFect transistors , Journal of Applied Physics 95, 5088 (2004). 

Figure 1 shows the symbols of common elements used in electronic circuits. These can be classed as either passive components, such as resistors, capacitors, inductors, and diodes, or active components, such as bipolar and field-effect transistors, and silicon-controlled rectifiers (SCRs). Some of the key features and physical characteristics of these devices are summarized in the first two sections of this chapter. 

One of the easiest ways to visualize the material and device characteristics that need to be measured is to consider a semiconductor device. For this I have chosen in Figure 1 a metal-oxide-semiconductor field-effect transistor (MOSFET) as representative of a typical semiconductor device. Indicated on it are the important material and device parameters that need to be measured. Only some of them are addressed in this chapter. Other devices could have been chosen, but the MOSFET incorporates most ot the parameters of interest and is the most coismon integrated circuit device. 

Because of these fundamental difficulties in applying the time-of-flight method for arbitrary molecular materials, today most mobilities known for molecular materials have in fact been extracted from the electrical characteristics of organic field effect transistors. There are several methods to extract the electron and hole mobilities from the electrical device characteristics of an OFET. For a more thorough description of the different procedures, the reader is referred to the paper by Scheinert and Paasch [13]. 

A number of recent articles also describe the influence of moisture and ambient gases on device characteristics of organic field-effect transistors (OFETs)... 

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