NORMAL INCIDENT INGAAS GAAS MULTIPLE-QUANTUM-WELL INFRARED DETECTOR USING ELECTRON INTERSUBBAND TRANSITIONS/

A normal incident infrared detector has been fabricated using electron intersubband transition in a InGaAs/GaAs quantum well structure. With the light polarized in the plane of the layers (normal incident) a no minally forbidden absorption peak was observed. Such an absorption is most likely a result of spin-flip intersubband transitions induced by the spin-orbit coupling. In addition, for the light polarized in the p lane of incidence, the usual intersubband absorption due to envelope f unction transition is observed. The responsivity of 0.2 A/W was obtain ed for the normal incident infrared on the detector. This work demonst rates the fabrication of high sensitivity quantum well infrared detect ors operating in the normal incident mode without fabricating grating structures on the device for focal plane applications. (C) 1995 Americ an Institute of Physics.