PHOTOLUMINESCENCE CHARACTERIZATION OF TE-DOPED GASB LAYERS GROWN BY LIQUID-PHASE EPITAXY FROM BI MELTS

Tellurium-doped GaSb epitaxial layers with electron concentrations in the range from 6 x 10(16)-5 x 10(18) cm(-3) are grown at 420 degrees C by liquid-phase epitaxy from Bi-based melts. The low-temperature phot oluminescence (PL) spectra of the layers with electron concentrations above 2 x 10(17) cm(-3) are dominated by a single broad band L1, which is attributed to a transition from the degenerated conduction band to the valence band. At electron concentrations <10(17) cm(-3) in additi on to L1 two new PL bands L2 and L3 are detected which are due to tran sitions of electrons to two different accepters. In the layers grown f rom Bi melts, the dominant background acceptor is not the GaSb antisit e-related native acceptor, but a much shallower acceptor with an ioniz ation energy of approximate to 11 meV. In addition, the layers are als o free from the deep antisite complexes VGaGaSbTeSb, which are the cha racteristic defects for Te-doped layers grown by liquid-phase epitaxy from Ga-rich melts, metal organic vapour phase epitaxy and molecular b eam epitaxy.