CHARACTERIZATION OF INXGA1-XP/GAAS GROWN BY GAS SOURCE MOLECULAR-BEAM EPITAXY (0.35-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-0.60) BY SPECTROSCOPIC ELLIPSOMETRY

The InGaP/GaAs system presents an attractive alternative to the GaAs/AlGaAs system for heterojunction devices because of its unique heterojunction properties and relatively small interface recombination velocity. A lack of sufficiently detailed optical characterization for probing the higher bands, however, led us to undertake an investigation utilizing spectroscopic ellipsometry. Samples studied were grown on (100) GaAs substrates by gas source molecular-beam epitaxy. The low-temperature photoluminescence linewidth was as narrow as 6.7 meV. Hall measurements showed a room-temperature electron mobility of 1500 cm2/V s and unintentionally doped "n"-type carrier concentration of 1.7 x 10(16) cm-3. The compositional dependence of the E1 gap of InxGa1-xP near lattice-matching conditions to the GaAs buffer for (0.35 less-than-or-equal-to x less-than-or-equal-to 0.60) and the broadening of the E1 gap have been studied utilizing the spectroscopic ellipsometry technique for the first time. The position of the E1 gap is found to be sensitive to growth conditions.