Hydrogenated Amorphous Silicon Electronic Devices and their Arrays

This chapter discusses the physics, fundamental limitations, and applications of the amorphous devices. The most attractive application of hydrogenated amorphous silicon (a-Si:H) electronic devices is in an active matrix. The chapter describes both the state-of-the-art technologies and performance of a-Si:H devices, and various technological trends aimed at achieving still further improvement. One-dimensional analytical theories are sufficient to grasp fundamental device physics, while two-dimensional numerical results give a design guide for high-performance and short-channel field-effect transistors (FETs). The most important parameter in a-Si:H FET characteristics, from the viewpoint of applications, is their on- and off-current, I_ON and IOFF. I_ON and I_OFF are drain currents when the gate voltage takes the maximum and minimum values, respectively, and depend on operating conditions. Many experimental results on the static performance of a-Si:H FETs have been obtained. These accumulated results gradually have clarified relations between FET performance and fabrication conditions and have identified remaining problems as well.