GROWTH OF HIGH-QUALITY INGAP AND APPLICATION FOR MODULATION-DOPED STRUCTURE BY MOLECULAR-BEAM EPITAXY WITH A GAP SOURCE

High-quality In0.48Ga0.52P lattice-matched to GaAs has been successfully grown by solid-source molecular beam epitaxy (MBE). To avoid the problem associated with white phosphorus, a dimer phosphorus molecular beam was produced by the sublimation of GaP. The In0.48Ga0.52P layers have been characterized by double-crystal X-ray diffraction (DCXR), photoluminescence (PL) spectroscopy and Hall measurements. The full width at half maximum of the (004) DCXR peak from 1.7 mu m thick layer is 13 are sec, which is comparable to the smallest value ever reported. The PL linewidth at 10 K is 16 meV and the electron mobilities are comparable to similar InGaP/GaAs layers grown by gas-source MBE. To confirm the layer quality for device application, InGaP layers were used for pseudomorphic AlGaAs/InGaAs/GaAs modulation-doped field-effect transister (MODFET) structures. Since wet chemical etchants with pronounced selectivity between InGaP and GaAs are well established, InGaP layers are attractive for the device fabrication as etch-stopper. In addition, Si-doped InGaP can replace the Si-doped AlGaAs layer, which causes the problem of persistent photoconductivity (PPC) at low temperatures. We have grown three different samples to compare the properties of the MODFET structures. The insertion of the etch-stopper did not deteriorate the properties of the MODFET structures and the PPC effect was significantly improved, although the carrier concentration was reduced.