Internal Photoemission and Energy Band Discontinuities at Semiconductor Heterojunctions

128 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1988.A new technique has been developed to measure the conduction band discontinuities ($\Delta$E$\sb{\rm c})$ at certain semiconductor heterojunctions. The technique involves measuring the spectral response of specially designed p$\sp{+}$N$\sp{-}$ heterojunction photodiodes. Internal photoemission from the valence band of the p$\sp{+}$ layer is observed in these devices and power law fits are used to accurately extract the threshold energy. A simple calculation then gives the size of the conduction band heterobarrier. Subsequent analysis of small barrier lowering effects allows $\Delta$E$\sb{\rm c}$ to be deduced directly, accurately, and reliably.This technique has been applied to GaAs-Al$\sb{\rm x}$Ga$\sb{\rm 1-x}$As (x $>$ 0.5) heterojunctions at room temperature and to Ga$\sb{0.47}$In$\sb{0.53}$As-InP heterojunctions over a temperature range of 135 K to 300 K.The results and advantages of this technique are compared to previous experimental efforts.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD