Photocurrent measurements of electric-field-induced carrier energy shifts and tunnelling in In1-xGaxAs/InP quantum wells

Abstract

The authors have measured photocurrent in In_1-xGa_xAs/InP quantum well samples as a function of temperature and applied electric field in order to study the escape of carriers initially photo-excited into the wells. For fields 8*10⁴ V cm^-1, there is suppression of the excitonic features in the spectrum which is attributed to a low exciton ionisation rate which causes carriers to recombine within the well rather than to undergo perpendicular transport. At higher fields, the authors observe strong Stark shifts of the excitons. They observe clear evidence of carrier tunnelling at low temperatures, and at higher temperatures they detect phonon-assisted tunnelling. The experimental results are shown to be in good agreement with the predictions of an exact theoretical calculation.