A study of the effect of V/III flux ratio and substrate temperature on theIn incorporation efficiency in InxGa1-x/GaN heterostructures grown by rf plasma-assisted molecular beam epitaxy

Laterally resolved high resolution X-ray diffraction (HRXRD) and photolumin escence spectroscopy (PL) have been used to assess In incorporation efficie ncy in InxGa1-xN/GaN heterostructures grown through rf-plasma-assisted mole cular beam epitaxy. Average alloy composition over a set of InxGa1-xN/GaN s uperlattices has been found to depend systematically upon both substrate te mperature (T-sub) and V/III flux ratio during growth. A pronounced thermall y activated In loss (with more than an order-of-magnitude decrease in avera ge alloy composition) is observed over a narrow temperature range (590-670 degreesC), with V/III flux ratio fixed. Additionally, the V/III flux ratio is observed to further strongly affect In incorporation efficiency for samp les grown at high T-sub, with up to an order-of-magnitude enhancement in In content despite only a minor increase in V/III flux ratio. PL spectra reve al redshifts as In content is increased and luminescence efficiency which d egrades rapidly with decreasing T-sub Results are consistent with In loss a rising from thermally activated surface segregation + surface desorption pr ocesses during,growth.