HEAVY CARBON DOPING IN LOW-PRESSURE METALORGANIC VAPOR-PHASE EPITAXY OF GAAS USING TRIMETHYLARSENIC - A COMPARISON BETWEEN THE CARRIER GASES N-2 AND H-2

The carbon doping behavior of trimethylarsenic (TMAs) in low-pressure metalorganic vapor phase epitaxy (LP-MOVPE) of GaAs was studied in the temperature range of 550 to 700 degrees C and at various trimethylars enic/trimethylgallium (TMAs/TMGa) ratios using the carrier gas N-2 in comparison to the standard H-2. At a growth temperature as high as 600 degrees C, perfectly specular layers with a hole concentration equali ng the carbon concentration of 1.7 x 10(20) cm(-3) and a mobility of 5 5 cm(2)/V.s were achieved for the carrier gas nitrogen. This is the hi ghest fully active carbon concentration ever reported for MOVPE materi al, to our knowledge, and more than double the hole concentration obta ined for the carrier hydrogen under the same growth conditions. This r esult indicates that the carrier N-2 is better suited for heavy carbon doping with TMAs at such a high growth temperature as 600 degrees C t han the carrier H-2, and is therefore more compatible to growth requir ements for (AlGa)As/GaAs heterostructures than H-2. A method is introd uced with which the accepters are activated without post-growth anneal .