Voltage‐tunable two‐color detection by interband and intersubband transitions in a p‐i‐n‐i‐n structure

We report on a novel class of voltage‐tunable two‐color detectors, based on a quantum‐well intersubband photodetector (QWIP) and a p‐i‐n photodiode in a p‐i‐n‐i‐n configuration. In this approach, the two constituting detector structures can be optimized independently because of their different conductance characteristics. The detection concept is demonstrated for the case of an 8‐10μm GaAs/AlGaAs QWIP and a 850 nm p‐i‐n diode containing In0.08Ga0.92As quantum wells.