Influence of the illumination on weak antilocalization in an Al _xGa_1-xN/GaN heterostructure with strong spin-orbit coupling

The weak antilocalization effects of the two-dimensional electron gas in a high mobility Al_xGa_1-xN/GaN heterostructure have been investigated by means of magnetotransport measurements before and after illumination. The zero-field spin splitting mainly arising from the Rashba spin-orbit coupling effect as a function of electron concentration as well as a function of temperature is studied using the weak antilocalization analysis. The Rashba spin-orbit coupling constant α deduced using the weak antilocalization analysis shows a rapid decrease with the increase of the measured electron concentration.