Ordering effects in MOCVD grown Ga 0.5In 0.5P on misoriented (100) GaAs

Abstract

The effects of substrate misorientation on the structural and optical properties of Ga 0.5In 0.5P on GaAs grown by low pressure metalorganic vapor phase epitaxy have been studied. The highest degree of ordering was found on the (100) exact substrates. The degree of ordering was found to decrease with the increase of misorientation angle toward all four directions, [111], [111], [110] and [101]; the most effective misorientation to disorder is tilted toward [111]. The band gap energy increases monotonically with increasing angle of misorientation. The value of the full width at half maximum (FWHM) is 14 meV for GaInP on 6° off toward [111] sample; this is among the narrowest FWHM ever reported at low temperature. For three other tilt directions, the FWHM initially increase at a small tilt angle and then decrease with increasing tilt angle. From these, we found the best misorientation is tilted toward [111] which has the disordered structure to achieve the high energy band gap and narrow FWHM.