Electro-optical examination of the band structure of ordered InGaAs

Using electroabsorption measurements, we have studied the effects of atomic superlattice ordering on the electronic band structure of InGaAs for diffe rent growth parameters. We have observed ordering-induced polarization anis otropy, valence-band splitting and band gap reduction strongest for 550 deg rees C growth and 2 degrees[111](B) tilted substrates. Back-folded conducti on-band states show an ordering dependent energy shift. The position of the split-off valence-band, however, is almost unaffected. An extension to ext remely low growth temperatures exhibits ordering also for 450 degrees C gro wth. Atomic force microscopy measurements reveal a temperature-dependent ch ange of InGaAs surface from step-like to island formation. (C) 2000 America n Institute of Physics. [S0003-6951(00)04401-6].