ABSTRACT

Improvement in the stability of molecular beam epitaxy (MBE) semiconductor processing is described employing concurrent engineering methods. MBE can produce materials from the order of a single atomic layer of deposition to sharp interlayer interfaces required for efficient optoelectronic GaAlAs multiquantum-well lasers. The variability of effusion cell flux values during material layer growth is further influenced by the performance of cell temperature control loops. A goal of in situ sensors is to provide material inspection during processing through nondestructive product evaluation. In situ measurement of MBE process mass–momentum–energy quantities is consequently of interest for enabling accurate thin-film growths by means of automatic control. A majority of process control systems include proportional-integral-derivative controllers for their environmental apparatus to obtain standard control functions including data exchange capabilities. A comprehensive MBE effusion cell variability characterization is further provided by a closed-loop cell measurement and control error analysis.