Effects of channel width and parasitic bipolar action on p-type poly-Si resistor characteristics

The effects of channel width on I-V characteristics of thin-film p-type poly-Si resistors are discussed, in particular for the case in which the resistor current is mainly due to field-enhanced generation of carriers at the drain end (as can be common at high drain electric field). A significant decrease in current per unit width (microamperes per micrometer) is observed as the channel width is reduced from 3 to 0.6 mu m. This decrease in current per unit width is due to the influence of fixed positive charge along the channel edges, which decreases the beta value associated with parasitic bipolar action in this regime of device operation.<>