Changes in crystal size and morphology were obtained by modifying the process for growing crystals of betasilicon carbide from solution in carbon-saturated melts. Well developed laths and plates were grown under conditions favoring dendritic growth mechanisms (low thermal gradient with moderate stirring). Polyhedral crystals grew under high thermal gradient conditions when high velocity stirring was employed. Three-dimensionaltype growth was also produced from a 73 wt percent ironsilicon alloy under conditions that normally produce lath-type growth. Uncorrected electron mobilities of 700 to 1000 sq cm/v-sec were measured at room temperature, and a few preliminary Hall measurements were made over the temperature range from 77 to 300 K. (Author).

The report summarizes the development program in the growth of large high purity beta silicon carbide crystals. Conditions for stable beta growth were partially established. Beta silicon carbide can be grown in the region of 2000-2200C and 28-42 microns pressure. Within this region, large beta crystals will grow by sublimation. Lang topographs of crystals were compared with etched surface structures and petrographic examination. Correlation among the results of these techniques was shown to exist. This analysis indicated the presence of large stacking faults within the structure as well as polytype intergrowths. Resistivity and Hall measurements were made with indications of highly compensated material. (Author).

Equipment and growth procedures for growing beta-silicon carbide epitaxially on beta-silicon carbide substrates from methyltrichlorosilane in a carrier gas of hydrogen is described. Hall and resistivity measurements and electron spin resonance measurements are discussed. The results show that the quality of the epitaxially grown material is comparable with that of the best solution grown crystals. Processing steps such as oxidation, masking, and etching have been performed and simple electroluminescent diodes have been fabricated. (Author).

The project involves the development of low pressure chemical vapor deposition and r-f sputtering techniques for the synthesis of single crystal thin films of beta-SiC. The CVD apparatus is being produced in-house and a detailed description of the design is provided herein. Theoretical CVD phase diagrams of the Si-C-H system are also being produced as a function of Si/Si+C and total pressure. Both reactive sputtering of Si in CH4 and normal sputtering of a SiC target are being readied. (Author).