Inhomogeneous and temperature-dependent p-InGaAs/n-InP band offset modification by silicon δ doping: An internal photoemission study

We measured by internal photoemission the conduction-band discontinuity ΔEc in p-In0.53Ga0.47As/n-InP heterojunctions with a Si δ layer (1×1012 cm−2) inserted in InP at 10 Å from the interface. The n-type Si δ doping induced an inhomogeneous and temperature-dependent conduction-band offset reduction as revealed by two onsets in the spectral response. The first one was absent in room-temperature data and was due to the Si intralayer presence. The second correlated with the conduction-band discontinuity value for heterojunctions without δ doping and its presence served as an indication of the inhomogeneity of the Si δ layer. The measured value of the modification was 0.11±0.04 eV in good agreement with the calculated one. Current-voltage measurements confirmed that the Si δ layer modified the transport parameters of the heterojunction only at low temperature.