Kinetic ellipsometry measurement of InGaP/GaAs hetero-interface formation in MOVPE

In order to fabricate monolayer (ML)-abrupt hetero-interfaces. we investiga ted the surface phenomena during MOVPE using in situ kinetic ellipsometry. We studied the adsorption/desorption kinetics of group-V atoms on InGaP sur face during gas-switching sequence to form InGaP/GaAs structure. When switc hing from InGaP growth to GaAs growth, first TMIn and TMGa supplies were st opped and excess amount of phosphorus was desorbed rapidly by stopping the TBP (tertiarybutylphosphine) supply. Purging monolayer phosphorus, which wa s bonded to In, or Ga required 0.8 s TBAs (tertiarybutylarsine) flow. No ar senic penetrated into the InGaP layer during TBAs introduction. Based on th ose observations, we devised optimum gas-switching sequence to obtain abrup t hetero-interface with ML unit. Photo-luminescence peak from the quantum w ell fabricated with this sequence shifted to shorter wavelength, showing th e effectiveness of this sequence. (C) 2000 Elsevier Science B.V, All rights reserved.