Sensor-based MOCVD for the growth of low surface resistance YBCO on MgO enabling Q's in excess of 100,000

Today MOCVD, due to its inherent advantages such as scaleability and throug hput, is the growth technique of choice for many compound semiconductors as a production method. However, the use of MOCVD to deposit high quality HTS material has been impeded by the lack of stable precursors. To overcome th e problems of limited process reproducibility caused by these shortcomings, real time control of the gas phase composition by ultraviolet absorption s ensors has been utilized. This technique allows for a very tight control of the composition of the deposited material. A surface resistance R-s lower than 250 mu Omega (77 K, scaled to 10 GHz) could be measured on 700 nm thic k MOCVD YBCO films. This value correlates very well with the surface resist ance extracted from measurements of the quality factor Q(0) of a simple mic rostrip resonator used as a process control monitor. Consistent surface res istance values below 350 mu Omega prove the reproducibility of the sensor b ased MOCVD approach. For cellular telecommunica-tion devices at 845 MHz qua lity factors Q(0) in excess of 100,000 at 77 K are indicative of the excell ent material quality.