Effects of surface passivation during atomic layer deposition of Al2O3 on In0.53Ga0.47As substrates

Abstract

In this work we investigate the effect of different III-V surface passivation strategies during atomic layer deposition of Al 2 O 3. X-ray photoelectron spectroscopy indicates that bare As-decapped and sulfur passiv-ated In 0.53 Ga 0.47 As present residual oxides on the surface just before the beginning of the Al 2 O 3 deposition while the insertion of a Ge interface passivation layer results in an almost oxide free Ge/III-V interface. The study of the initial growth regimes, by means of in situ spectroscopic ellipsometry, shows that the growth of Al 2 O 3 on Ge leads to an enhanced initial growth accompanied by the formation of Ge-O-Al species thus affecting the final electrical properties of the stack. Alternatively, deposition on decapped and S-passivated In 0.53 Ga 0.47 As results in a more controlled growth process. The sulfur passivation leads to a better electrical response of the capacitor that can be associated to a lower oxide/semiconductor interface trap density.