Characterization of semiconductor heterojunctions using internal photoemission

Internal photoemission is a photoelectric characterization technique commonly used to study semiconductor heterojunction characteristics. Previous analyses of internal photoemission including those of Fowler, Kane, and Powell have been well accepted and applied; however, the quantum effects were not fully taken into account. We examined the quantum effects on internal photoemission spectra and found that the photoemission yield, Y(hν), is proportional to (hν-E_T)^γ, where hν is the photon energy, E_T is the threshold energy, and γ is a constant determined by the emitter density of states, the transmission probability, and the collector conduction band density of states, respectively.