Photocurrent spectroscopy of intersubband transitions in GaInAsN/(Al)GaAs asymmetric quantum well infrared photodetectors

We have studied the conduction band electronic level structure of GaInAsN/(Al)GaAs-based quantum well (QW) infrared photodetectors using intersubband photocurrent (PC) spectroscopy and dark current analysis. Photoluminescence and intersubband absorption were carried out as complementary spectroscopic techniques. Based on the observed transition energy, we associated the photocurrent peaks with electron excitations from bound states in the quantum wells to quasi-bound states in the continuum. A good agreement with the experimental results was obtained using a 10-band k · p model that took into account the inhomogeneous distribution of nitrogen atoms along the quantum wells growth direction.