Strain relaxation by < 100 > misfit dislocations in dilute nitride In_xGa_(1-x)As_(1-y)N_y/GaAs quantum wells

摘要

The effect of dilute N alloying and Bi surfactant growth on strain relaxation in highly strained InGaAs single quantum well (QWs) was investigated by using high resolution X-ray diffraction (HRXRD) and transmission electron microscopy (TEM). Dilute nitride In_xGa_(1-x)As_(0.99)N_(0.01) QWs of varying thickness, constant lattice mismatch 1.7%, were grown by molecular beam epitaxy on oriented GaAs (001) substrates. Some samples were exposed to a flux of Bi surfactant during the growth procedure, which acts to enhance the N incorporation, increase the optical emission, and create smoother interfaces. The QWs were observed to relax through the formation of pure edge-type, misfit dislocations aligned with in-plane < 100 > directions. These were found to be directly associated with degradation in the optical emission, however, 1% N addition, with or without Bi surfactant, did not have a detectable effect on the critical thickness nor the rate of this relaxation mechanism.