The preparation of low defect density LPE garnet films for magnetic bubble device fabrication

Abstract

In order to study the cause and to eliminate magnetic domain pinning defects in (YSmLuCa)3(GeFe)5O12 LPE garnet films for use in magnetic bubble devices, a series of experiments have been conducted whereby Gd3Ga5O12 substrates have been intentionally contaminated with specific contaminants likely to be encountered in the substrate preparation and LPE film growth environments. The defects occuring in the films grown on these contaminated substrates have been examined by scanning electron microscopy at high magnifications. The exercise has enabled the identification of the causes of specific defects which occur during routine LPE growth. Other defects resulting from inadequate substrate preparation are discussed with emphasis on defects arising from garnet fragments associated with poor quality wafer edges. As a consequence of this study, defects densities <0.5 cm-2 have been achieved routinely in pilot production quantities on 2 inch diameter substrates.