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Si-delta-doped Al/sub 0.25/Ga/sub 0.75/As/In/sub x/Ga/sub 1-x/As (x=0.15-0.28) P-HEMT's, prepared by LP-MOCVD, are investigated. The large conduction band discontinuity leads to 2-DEG density as high as 2.1/spl times/10/sup 12//cm/sup 2/ with an electron mobility of 7300 cm/sup 2//V/spl middot/s at 300 K. The P-HEMT's with 0.7/spl times/60 /spl mu/m gate have a maximum extrinsic transconductance of 380 mS/mm, and a maximum current density of 300 mA/mm. The S-parameter measurements indicate that the current gain and power gain cutoff frequencies are 30 and 61 GHz, respectively, The RF noise characteristics exhibit a minimum noise figure of 1.2 dB with an associated gain of 10 dB at 10 GHz. Due to the efficient doping technique, the electron mobility and transconductance obtained are among the best reported for MOCVD grown P-HEMT's with the similar structure.