Photoluminescence spectroscopy is used to investigate interface roughness effects on electron and hole tunneling through GaAs/In0.1Ga0.9As/AlAs double-barrier tunneling structures. Typical quantum-well photoluminescence spectra present a splitting of 8 meV due to interface roughness and island formation in the quantum well. The states of these islands are selectively populated by electrons and holes by applying bias and changing the photon excitation intensity. Carrier transfer mechanisms between islands are clearly identified as well as intersubband scattering in a sequential tunneling picture. The measurement of activation energies as a function of bias provides an estimate for the electron density in resonant tunneling condition for diodes showing up islands at the interfaces. The possibility of observing growth island effects in I(V) characteristics is also carefully discussed. © 1999 The American Physical Society.