(DARK LINE DEFECTS, BRIGHT LINE LASERS)-MICROSCOPIC STUDIES OF SINGLE-SHOT LASING IN CDSE QUANTUM-WELLS

A preliminary report on single quantum well (SQW) lasers of CdSe grown by metalorganic vapour phase epitaxy (MOVPE) in a matrix of ZnSe is p resented. The total device thickness is 3 mu m. The quantum wells are ''ultrathin'' in the range from 0.5 to 2 monolayers (ML). The time-int egrated spectra of spontaneous emission from the top surface of as-gro wn samples are compared with spontaneous and stimulated edge emission from cleaved laser cavities. Such temporally and spatially integrated spectra are contrasted with single-shot laser spectra obtained by adap ting a 1 m single monochromator to operate as a videospectrograph. In addition to ''hidden'' mode structure, the spectrograms reveal the str ongly heterogeneous character of laser emission from these samples: br ight lines that indicate materials of good quality are found adjacent to dark lines where the emission is weak or absent.