Control of ordering in Ga0.5In0.5P using growth temperature

The kinetic processes leading to ordering in Gas,, In o.4P8 have been studied by observing the effects of substrate misorientation (O-9), growth rate (0.1-0.5), and substrate temperature (570- 670 "C) during growth. The ordered structure and degree of ordering are determined using transmission electron microscopy and photoluminescence (PL) spectroscopy. Low growth rates were used for samples with misorientations of O"-9" toward the [110] lattice direction to elucidate the ordering mechanism; however, due to the long times required to grow layers thick enough for PL characterization (-1 pm), at a temperature of 670 "C the samples became less ordered with increasing misorientation angle, This was attributed to a disordering annealing process occurring during growth which leads to disorder. In order to reduce the rate of this annealing process, the growth temperature was reduced from 670 to 570 "C. At this temperature, a growth rate of 0.5 pm/h produces material with an increasing degree of order as the angle of substrate misorientation is increased from 0" to 9". This shows that the kinetics of the ordering process are assisted by an increasing density of [110] steps on the surface.