A sub-atmospheric (SA) pressure gas source. based on the reversible adsorption of hydride gas onto a high surface area substrate within a cylinder, has been developed for the safe storage and delivery of high-purity arsine and phosphine for MOCVD processes. SA pressure and high-pressure sources are compared with respect to gas delivery and purity. risk reduction, and cost benefits. Gas analysis and performance of epi-structures grown With SA pressure cylinders confirm that the hydride gas delivered meets the purity requirements of MOCVD processes. Further, the low gas release rates measured from 2.2 and 49 1 SA pressure cylinders indicate that the technology can be scaled up without additional safety risk. (C) 2002 Elsevier Science B.V. All rights reserved.