Quality improvement of GaInNAs/GaAs quantum wells grown by plasma-assistedmolecular beam epitaxy

The optimum growth condition of GaInNAs/GaAs quantum wells (QWs) by plasma- assisted molecular beam epitaxy was investigated. High-resolution X-ray dif fraction and photoluminescence (PL) measurements showed that ion damage dra stically degraded the quality of GaNAs and GaInNAs QWs and that ion removal magnets can effectively remove the excess ion damage. Remarkable improveme nt of PL intensity and obvious appearance of pendellosung fringes were obse rved by removing the N ions produced in the plasma cell. When the growth ra te increased from 0.73 to 1.2 ML/s, the optimum growth temperature was rais ed from 460 degreesC to 480 degreesC and PL peak intensity increased two ti mes. Although the N composition decreased with increasing growth rate, degr adation of optical properties of GaInNAs QWs was observed when the growth r ate was over 0.92 ML/s. Due to low-temperature growth of GaInNAs QWs, a dis tinctive reflection high-energy electron diffraction pattern was observed o nly when the GaAs barrier was grown under lower As-4 pressure. The samples with GaAs barriers grown under lower As-4 pressure (V/III ratio about 24) e xhibited seven times increase in PL peak intensity compared with those grow n under higher As-4 pressure (V/III ratio about 50). (C) 2001 Elsevier Scie nce B,V. All rights reserved.