Download or read book Development and Evaluation of Die Materials for Use in the Growth of Silicon Ribbons by the Inverted Ribbon Growth Process Task II LSSA Project Quarterly Report No 5 October 1 December 31 1978 written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Several ribbon growth experiments were performed in the Mark II ribbon growth facility from V-shaped dies coated with CVD Si3N4. The most significant result was the ability to perform five consecutive growth runs from the same die without mechanical degradation of the die through temperature cycling. The die was made from vitreous carbon coated with CVD Si3N4. Silicon oxynitride, Si2N2O, was examined with respect to thermal stability in contact with molten silicon. The results of x-ray analysis indicate that this material is converted to both .cap alpha.- and .beta.-Si3N4 in the presence of molten silicon. The latter phase is the dominant phase. Experiments on the stability of CVD SiO3 /sub y/ show that this material can be maintained in contact with molten silicon (sessile drop test) for greater than 30 h at 1450°C without total decomposition. These layers are converted mainly to .beta.-Si3N4. The fabrication of coated EFG-type dies is proving difficult because of thermal expansion mismatch between layer and substrate and instability of substrate materials at high temperature. Self-supporting CVD dies have been prepared on silicon substrates but the wall thickness is not greater than about 50 .mu.m. Experiments are continuing.
Download or read book Development and Evaluation of Die Materials for Use in the Growth of Silicon Ribbons by the Inverted Ribbon Growth Process Task II LSSA Project written by M. T. Duffy and published by . This book was released on 1978 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development and Evaluation of Die Materials for Use in the Growth of Silicon Ribbons by the Inverted Ribbon Growth Process Task II LSSA Project written by M. T. Duffy and published by . This book was released on 1977 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1980 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development and evaluation of die materials for use in the growth of silicon ribbons by the inverted ribbon growth process task II LSSA project written by RCA Laboratories and published by . This book was released on 1978 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Solar Energy Update written by and published by . This book was released on 1978 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development and Evaluation of Die Materials for Use in the Growth of Silicon Ribbons by the Inverted Ribbon Growth Process written by and published by . This book was released on 1977 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Silicon sessile drop experiments were performed on a variety of commercially available refractory carbides, nitrides, oxides, and borides to examine the potential of these materials for applications involving either direct contact with molten silicon or as substrates for CVD coatings in the fabrication of dies and crucibles for containing molten silicon. Simultaneous experiments were also conducted with CVD layers of SiC, Si3N4, and SiO3 /sub y/. The latter two materials proved superior for purposes of contact with the silicon melt in relation to chemical reactivity and reduced impurity content. Silicon nitride layers, deposited with NH3 : SiH4 ratios ranging from 100 : 1 down to 5 : 1, were examined in sessile drop experiments to determine if the layers are degraded as a result of using lower reagent ratios. The cost of ammonia (5 nines purity) at the higher ratios represents the major cost in the production of these layers, and a reduction in the above ratio could result in a substantial reduction in cost. Preliminary experiments were undertaken on the stability of CVD Si3N4 near the melting point of silicon. From our initial experiments it appears that the rate of decomposition is less than 100 A/h just below the melting point of silicon. Silicon ribbon segments were grown from vitreous carbon dies which had been coated with CVD Si3N4. Depending upon the purity of the die materials, ribbon resistivity values up to 40 .cap omega.-cm were obtained.
Download or read book Government Reports Annual Index written by and published by . This book was released on 1979 with total page 948 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.
Download or read book Government Reports Annual Index Keyword A L written by and published by . This book was released on 1979 with total page 840 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development and Evaluation of Die Materials for Use in the Growth of Silicon Ribbons by the Inverted Ribbon Growth Process Task II LSSA Project written by RCA Laboratories and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1980 with total page 1182 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development and Evaluation of Die Materials for Use in the Growth of Silicon Ribbons by the Inverted Ribbon Growth Process written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The thermal stability of CVD SiO3 /sub y/ layers in contact with molten silicon has been studied by x-ray analysis. The results indicate that these layers are converted to the .cap alpha. and .beta. phases of Si3N4 with the .beta. phase predominating. Results to date indicate that the .beta. phase is the more stable form in contact with molten silicon. This explains why CVD oxynitride layers appeared to be more stable in contact with molten silicon than CVD Si3N4 layers in previous experiments. The oxygen present in the oxynitride layers is apparently removed during contact with the silicon melt with simultaneous conversion to Si3N4, principally the .beta. form. High-density hot-pressed Si3N4 has been prepared using MgO as binder. This material was found to be .beta.-Si3N4 by x-ray diffractometry and displayed excellent chemical inertness to molten silicon. The purity of the material was also much superior to that of hot-pressed material purchased externally. Mullite crucibles displayed some high-temperature instability effects which may influence the bonding of CVD layers to the mullite surface. The Mark II ribbon growth apparatus has been installed and tested.
Download or read book Development and Evaluation of Die Materials for Use in the Growth of Silicon Ribbons by the Inverted Ribbon Growth Process Task II written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of emission spectroscopic analysis indicate that molten silicon (sessile drop) can remain in contact with hot-pressed Si3N4 (99.2% theoretical density) for prolonged periods without attaining the impurity content level of the nitride. It is interesting to note that, although MgO was used as binder (approx. 3.8%), Mg was not found present in the silicon sessile drop in quantities much above the level initially present in the silicon source material. The conversion of CVD silicon oxynitride to .beta.-Si3N4 can be carried out at high temperature in N2 (approx. 1600°C), by contact with molten silicon or by a combination of these steps. Conversion in the presence of molten silicon appears preferable. Preliminary experiments with EFG-type dies coated with CVD Si3N4 or CVD SiO3 /sub y/ indicate that capillary rise does not occur readily in these dies. The same was found to be true of hot-pressed and reaction-sintered Si3N4 obtained commercially. However, when dies were formed by depositing CVD layers on shaped silicon slabs, a column of molten silicon (approx. 2.5 cm high) was maintained in each CVD die while being heated (approx. 30 min) in contact with a crucible of molten silicon. Preliminary wetting of dies appears necessary for EFG growth. Several ribbon growth experiments were performed in our new ribbon growth facility from V-shaped dies. Both CVD Si3N4 and CVD SiO3 /sub y/ coatings were used on the die parts. There is also a problem with the wetting of SiO3 /sub y/ in the inverted ribbon growth process but not with Si3N4 layers. After about 90 min in contact with the melt, however, silicon flows into the defining slot in the case of SiO3 /sub y/ coatings.
Download or read book Development and Evaluation of Die Materials for Use in the Growth of Silicon Ribbons by the Inverted Ribbon Growth Process Task II LSA Project Final Report October 1 1977 March 31 1979 written by and published by . This book was released on 1979 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Amorphous CVD layers of silicon nitride and silicon oxynitride are prepared by chemical vapor deposition (CVD). The CVD layers are converted to .cap alpha.- and .beta.-Si/sub 3/N/sub 4/ in contact with molten silicon. Silicon nitride layers are converted initially to .cap alpha.-Si/sub 3/N/sub 4/ with a low .beta.-Si/sub 3/N/sub 4/ content. The .cap alpha. phase is then slowly converted to the .beta. phase accompanied by simultaneous decomposition. By contrast, silicon oxynitride (SiO/sub x/N/sub y/) layers are converted predominantly to .beta.-Si/sub 3/N/sub 4/ with a low .cap alpha.-Si/sub 3/N/sub 4/ content. In this process, oxygen is evolved, and there is no evidence for the existence of an oxynitride phase in the resulting layers. The analysis also indicates that .beta.-Si/sub 3/N/sub 4/ is much more resistant to chemical attack by molten silicon than .cap alpha.-Si/sub 3/N/sub 4/. Consequently, CVD silicon oxynitride provides a useful means of obtaining relatively pure and inert .beta.-Si/sub 3/N/sub 4/ as a substrate coating for prolonged exposure to molten silicon, while CVD silicon nitride coatings are useful for shorter exposure times. Crystallographic analysis of silicon ribbon test specimens, grown from CVD-coated vitreous carbon dies, indicates that silicon carbide inclusions are not present in the ribbon samples. The results of infrared analysis also show that the carbon content of the silicon ribbons is below detection level and lower than in the Czochralski seed material.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1979 with total page 684 pages. Available in PDF, EPUB and Kindle. Book excerpt: Includes all works deriving from DOE, other related government-sponsored information and foreign nonnuclear information.
Download or read book Study Program to Develop and Evaluate Die and Container Materials for the Growth of Silicon Ribbons written by and published by . This book was released on 1979 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study Program to Develop and Evaluate Die and Container Materials for the Growth of Silicon Ribbons Quarterly Report written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
