GSMBE growth of InGaP/(In)GaAs modulation-doped heterostructures and their applications to HEMT and HHMT

In this paper we report for the first time gas-source molecular beam epitaxy of both n- and p-channel InGaP/(In)GaAs modulation-doped heterostructure. The sheet density dependence of the two-dimensional hole gas (2DHG) mobility of p-type In0.49Ga0.51P/GaAs structures was investigated by Van der Paul Hall measurement at 300 and 77K. The 2DHG densities of 2.78×1012 and 1.02×1012cm−2 with mobilities of 191 and 2831cm2/Vs at 300 and 77K, respectively, for In0.49Ga0.51P/GaAs structures have been achieved. Low-temperature and high-magnetic field Hall measurements were also carried out. Longitudinal resistance of the structure shows two oscillations with different periods at a temperature of 0.3K, indicating that two subbands have been occupied by holes in the GaAs channel. The sheet density for each subband was estimated to be 1.22×1012 and 0.77×1012cm−2, respectively. Both high hole mobility transistors (HHMTs) and high electron mobility transistors (HEMTs) were demonstrated. HHMTs show a maximum DC transconductance of 35mS/mm. The saturation current is 57mA/mm at 300K with Vd=−3V. Both extrinsic transconductance and saturation current of our novel In0.49Ga0.51P/GaAs HHMTs are well improved, compared with those of AlGaAs/GaAs and InGaAs/GaAs HHMTs. Enhanced-mode InGaP/InGaAs pseudomorphic HEMTs were achieved with a maximum DC transconductance of 250mS/mm.