GAS-SOURCE MOLECULAR-BEAM EPITAXY OF LATTICE-MATCHED GAXIN1-XASYP1-Y ON GAAS OVER THE ENTIRE COMPOSITION RANGE

We have grown lattice-matched GaxIn1-xAsyP1-y on GaAs over the entire composition range (0 < y < 1) using the gas-source molecular beam epit axy technique. The growth features and material properties for these e pilayers have been investigated. The group-V incorporation efficiencie s, described by S(As) and S(P) as the ratios of As and P in solid to g as phase, differ from those of S(As) and S(P) for lattice-matched GaxI n1-xAsyP1-y on InP. S(As) and S(P) in lattice-matched GaInAsP/GaAs are related to each other in such a way that 1 less than or equal to S(As )/S(P) less than or equal to 3 for 0 < y < 1. Distinct excitonic and d onor-acceptor radiative transitions are observed in photoluminescence (PL) measurements for the GaInAsP having (1 - x) less than or equal to 0.13 and a PL full-width at half-maximum of the main peak as small as 2.5 meV is obtained. For the GaInAsP having (1 - x) greater than or e qual to 0.2, the excitonic and donor-acceptor transitions overlap with each other, and the PL spectra become significantly broader. The ener gy bandgap and phosphorus composition of GaInAsP increase with increas ing growth temperature, due to the enhanced desorption of arsenic from the growing surface at elevated temperatures. Increasing growth tempe rature causes a reduction in impurity incorporation and improvement in crystalline quality. The as-grown GaInAsP/GaAs layer contains defects such as atomic clusters and vacancies. Annealing reduces the defects. Bowing of the band structure of GaInAsP/GaAs is also observed.