PSEUDOMORPHIC N-INGAP/INGAAS/GAAS GROWN BY MOVPE FOR HEMT LSIS

InGaP/InGaAs/GaAs heterostructures were grown by atmospheric pressure MOVPE. Excellent uniformity was obtained for doping concentration, thickness, and composition of the epitaxial layers by rotating the substrate and cooling the inner tube. The optimum gas switching sequence for achieving sufficient mobility and sheet carrier concentration was found. Enhancement-mode and depletion-mode HEMTs were fabricated using the very thin InGaP layer as an etching stopper layer. These are essential for the fabrication of HEMT LSI circuits. The discrete devices do not exhibit I-V collapse at low temperature. Short channel effects are negligible for gate lengths as small as 0.15-mu-m, owing to good carrier confinement in the pseudomorphic quantum well channel and a high aspect ratio under the thin n-InGaP layer. These advantages make InGaP/InGaAs/GaAs heterostructures well suited to HEMT LSIs applications.