MOVCD growth of selectively doped AlInAs/GaInAs heterostructures

Abstract

Selectively doped AlInAs/GaInAs heterostructures lattice matched to InP substrates have widely been studied because of their high mobility and large discontinuityof conduction band edge. The heterostructures had usually been grown by MBE; however, we succeeded in the growth of device-quality selectively doped AlInAs/GaInAs heterostructures by atmospheric-pressure MOVCD using trimethylmetals as source materials. The source materials of the III group and arsine of the V group were mixed near the leading edge of the substrate to minimize the parasitic gas phase reactions. The gas flow sequence introducing AsH3, and the metalorganic sources is critical to the surface morphology of the GaInAs and AlInAs layers. An undoped GaInAs layer with high purity (n=8×1014 cm−3, μ=12,400 cm2/V·s at room temperature) was obtained at the growth temperture of 640°C. maximum electron mobility of the two-dimensional electron gas was 12,400 cm2/V·s at room temperature and 76,900 cm2/V·s at 77 K for a sample with an undoped AlInAs spacer layer 50 Å thick and a sheet electron density of 1.8×1012 cm−2. We fabricated HIFETs (Hetero-Interface FETs) using these heterostructures. The HIFETs, 0.7 μm in gate length, showed good pinch-off characteristics with a transconductance of 680 mS/mm at room temperature and 870 mS/mm at 77 K.