A MOSFET that is fabricated using thin-film techniques on an insulating substrate rather than on a semiconductor chip. The insulating substrate reduces the bulk capacitance of the device and hence the operating speed can be increased. The technique was originally used for the fabrication of discrete cadmium sulphide transistors and the films could be deposited on the substrate in the order semiconductor, insulator, metal or vice versa. The technique is now used mainly for the construction of silicon-on-insulator CMOS circuits. TFT technology is also used to make flat-panel displays as an active matrix LCD (see liquid crystal display), often found in personal digital assistants (PDAs), laptop computers, and flat-panel displays for desktop computers and televisions. The technology employs thin semiconductor transistors to control the transmission of light of different colours for each pixel of the screen. Some of the advantages of TFT technology are that it provides the best resolution of all flat-screen technologies available at present, does not require any back lighting, and is daylight viewable. However, it is expensive.