SI DELTA-DOPED GAAS AND ALGAAS BY LOW-PRESSURE MOVPE

Delta doping of Si in GaAs and Al0.22Ga0.78As by low-pressure MOVPE ha s been explored for varying growth interruption times and SiH4 partial pressures. The resultant sheet concentrations could be interpreted ac cording to the total amount of SiH4 introduced. Saturations in sheet d ensity were observed at 6.6 x 10(12) and 3.6 x 10(12) cm(-2) in GaAs a nd Al0.22Ga0.78As, respectively. Mobility results were obtained for a range of different sheet concentrations at both 300 and 77 K. Hall mea surements on single delta-doped pseudomorphic high electron mobility t ransistor devices showed a maximum sheet density of 3.4 x 10(12) cm(-2 ) at 300 K and 4.3 x 10(12) cm(-2) at 77 K with mobilities of 2350 and 2700 cm(2) V-1 s(-1), respectively. The maximum extrinsic transconduc tance of such devices was 400 mS mm(-1) with a corresponding saturatio n current of 360 mA mm(-1) for 0.5 mu m gate length devices.