Important advances have been made in five technical areas during this quarter: topological investigations of film materials and cells, characterization of current transport and collection in Cu/sub 2/S/CdS cells, preparation and application of small area film cells, correlation of photoresponse image and structural features in film cells and means of preparing (CdZn)S alloy films. The use of potassium cyanide etching of Cu/sub 2/S layers on polycrystalline CdS films defined areas 1 to 5 ..mu..m across with the latter covering 30 to 50% of the surfaces studied. Large grains may strongly reduce short circuit current levels. Laser scanned photocurrent response of tapered Cu/sub 2/S layers on single crystal CdS has been refined to directly treat photocurrent-transmission data, allowing more firm estimates of lifetime, surface recombination velocity and heterojunction collection efficiency. Delineation of small area film cells has been done successfully using photolithographic methods. As used, these methods have no deleterious influence on cell behavior. With arrays of small cells on a single substrate it was possible to establish that increased junction opposing current (lower V/sub OC/) results from longer immersions in CuCl during Cu/sub 2/S formation. Patterns of high response in laser-scanned photocurrent images have been correlated with SEM images of …

The limits of blade tolerances are defined. The standard blades are T-2 thickness tolerance: T-O blades are unacceptable. Further testing is necessary to demonstrate feasibility or infeasibility of T-1 blades. Good results have been obtained by using a slurry fluid consisting of mineral oil and a lubricity additive. Cost would be about $0.25 per gallon per run, 1/4 of the cost goal. Adjustments of the formulation and fine tuning of the cutting process with the new fluid are necessary. Test results and consultation indicate that the blade breakage encountered with water based slurries is unavoidable. Two full capacity (974 wafer) runs have been made on the large prototype saw. Both runs resulted in extremely low yield, however, the reasons for the low yields were lack of proper technique rather than problems with machine function. Finally, the tests on the effect of amount of material etched off of an as-sawn wafer on solar cell efficiency have been completed. The results agree with previous work at JPL in that the minimum material removed per side that gives maximum efficiency is on the order of 10 ..mu..m.