Stepper Motor Control Using Microprocessor for Preparation of Homogeneous Compound Semiconducting Materials

: The various properties such as optical, electrical and device characteristics of compound semiconductor films depend critically upon the composition, stoichiometry and the homogeneity of their bulk compounds. Therefore, the identification and control of the composition and related characteristics of these materials are important. Thus, if a compound semiconductor thin film (binary, ternary or still more complex) is to be prepared by various deposition techniques, it is usually necessary to have the evaporant charge in a compound form with homogeneity and stoichiometry. Here we have developed a setup of microprocessor based stepper motor control to get homogeneous growth of compound material by continuously mixing the evaporant charge kept in vacuum sealed quartz ampoule at high temperature using furnace. The shaft of the stepper motor is connected to the quartz ampoule via proper mechanical coupling arrangement. The stepper motor is interfaced with programmable peripheral interface IC 8255 which is controlled by microprocessor 8085. Suitable instrumentation is developed to drive the stepper motor having step angle of 1.8o. We can change the speed of the motor by suitable programming as per requirement. The detail implications are discussed.