Growth Processing And Characterization Of Beta Silicon Carbide Single Crystals

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).

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).

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).

Beta silicon carbide has the potential of becoming an important semiconductor device material for hazardous military environments such as high temperature and radiation. This report is concerned with a study of the growth of thin single crystal films of beta silicon carbide through molten metal intermediates. Thin films of nickel, cobalt, chromium and iron were deposited by vacuum deposition on to the (0001) faces of single crystals of alpha silicon carbide. Then heteroepitaxial layers of beta silicon carbide were deposited through the molten metal films by the hydrogen reduction of methyltrichlorosilane. The deposited films were studied by electron microscopy, electron diffraction and electron beam microprobe analysis to determine the growth mechanism and to arrive at optimum conditions for heteroepitaxial growth. From the results obtained it was concluded that nickel and cobalt were equally effective in promoting epitaxial growth. Films of nickel only 20A in thickness were as effective as those up to 300A. Results with chromium and iron were disappointing for different reasons. Chromium did not etch the substrate surface uniformly because of poor wetting. With iron, whisker growth of beta silicon carbide occurred at the surface. Although in many respects the growth of mechanism resembled that of the vapor-liquid-solid method, certain differences were observed which make the actual growth mechanism using nickel and cobalt films still uncertain. (Author).

Silicon Carbide — 1968 presents the proceedings of the International Conference on Silicon Carbide held in University Park, Pennsylvania on October 20-23, 1968. The book covers papers about the perspectives on silicon carbide; several problems in the development of silicon carbide semiconductors, such as the control of crystal structure and analysis. The thermal properties of beta-silicon carbide from 20 to 2000 degrees and the influence of impurities on the growth of silicon carbide crystals in chemical reactions and by recrystallization are also discussed. The book then presents papers about silicon carbide single crystal growth using the Norton process; the principles of solution and traveling solvent growth of silicon carbide; the growth of silicon carbide from cobalt-silicon solutions; and the growth of silicon carbide from vapor by the Bridgman-Stockbarger method. Papers about the growth of crystals and epitaxial layers of beta silicon carbide; the heteroepitaxy of beta-silicon carbide employing liquid metals; some aspects of disorder in silicon carbide; and the dependence of physical properties on polytype structure are also considered. The book describes topics about the optical properties of polytypes of silicon carbide as well as the phase stability of silicon carbide against nitrogen. Other papers about the physical and electronic properties of silicon carbide are also discussed in the book. People involved in semiconductor industries will find the book helpful.