IMPROVED GAAS IN0.25GA0.75AS GAAS PSEUDOMORPHIC HETEROSTRUCTURE BY GROWING DOUBLE DELTA-DOPING GAAS-LAYERS ON BOTH SIDES OF THE CHANNEL

A novel GaAs/In0.25Ga0.75As/GaAs heterostructure field effect transist or with delta-doping of the GaAs on both sides of the InGaAs channel h as been grown by low-pressure metalorganic chemical vapor deposition ( LP-MOCVD). Very high two dimensional electron gas (2DEG) concentration of 5.1 and 3.4 x 10(12) cm-2 at 300 and 77 K respectively, along with enhanced electron mobilities of 4500 and 14100 cm2/v . s at 300 and 7 7 K respectively, were achieved. A maximum extrinsic transconductance of 140 mS/mm and a high saturation current density of 460 mA/mm at 300 K for a gate length of 2 mum, were obtained. A broad transconductance region extending from reverse to forward gate bias was observed due t o the double delta-doped GaAs grown symmetrically on both sides of the channel.