Equipment for the production and assessment of thin-film display devices

Abstract

Work carried out in the Department on solid-state display devices based on thin films of willemite (Zn(_2)SiO(_4)iMn) on silicon substrates has shown the need for a cleaner vacuum environment during preparation, and particularly has shown the usefulness of capacitance-voltage measurements in determining the physical behaviour of the structures. Other workers have shown the use of conductance-voltage measurements also. This thesis describes equipment designed and built to meet the above requirements. A stainless steel ultra-high vacuum system, with an electron beam evaporator and provision for an electron bombardment substrate heater is described for use in the fabrication of thin film display devices. A clean environment at pressures down to 10(^-8) torr is provided by sorption and sputter ion pumps. The apparatus includes electronic equipment used for control no during long periods of unattended pumping, baking or evaporation. Instrumentation for the assessment of the display devices (and other metal-insulator-semicoxiductor structures) has been developed, including a C-V Plotter, an I-V Plotter and a high performance conductance-capacitance (G-C-V) Plotter capable of measuring device parameters over a wide range of values and test frequencies.