MOCVD Growth and Characterization of Pseudomorphic HEHT's in a High Speed Rotating Disk Reactor

Until recently, nearly all of the major work on pseudomorphic HEMTs has been dominated by MBE technology. Low throughput is an inherent problem with MBE equipment. For this reason EMCORE proposes to use its low pressure, high speed, rotating disk MOCVD technology for the deposition of pseudomorphic HEMT structres. The technology is scaleable so that increasing the growth chamber size to accomodate growth runs of multiple 4 in. wafers should be possible. ENCORE proposes in phase I to extend our GaAs/AIGaAs HEMT technology to the pseudomorphic HEMT structure. We will examine the In fraction InGaAs layer thickness to optimize the mobility of the structure. These will be a "characterization" structure grown which has an undoped GaAs cap layer so that both 300 k and 77k Hall effect measurements may be done. Also, a sheet resistivity map of the entire wafer is generated to insure film uniformity. The inital growth runs will be done on 2 in. diameter substrates. When the process has been optimized the growths will be done on 4 in. diameter wafers. These wafers will again have the sheet resistivity map prepared. Nine samples will then be cleaved in a cross pattern. 300k and 77k Halleffect measurements will be performed to examine uniformity of mobility. The most promising 2 in. sample will be sent to our consultant for device fabrication and testing. A complete device wafer (GaAs cap layer will be doped) will be made available to the Air Force for further device processing.