Domain pinning in GaAs/AlGaAs quantum well infrared photodetectors

We have analyzed the spatial distribution of electric field domains induced by negative differential photoconductivity in n-type GaAs/AlGaAs quantum well infrared photodetectors. We find strong evidence of two different domain configurations, with the high-field domain and the low-field domain, respectively, adjacent to the emitter contact. A distinctive signature of these domain configurations is provided by the observed total current, which is observed to be close to either the valley current or the peak current. We also discuss the emergence of the two configurations.