Metal Hole Arrays as Resonant Photo-Coupler for Charge Sensitive Infrared Phototransistors

Metallic photo-couplers utilizing surface plasmon polariton (SPP) excitation have been studied experimentally and theoretically for improving the quantum efficiency of charge sensitive infrared phototransistors (CSIP). Metallic hole arrays deposited on top of the photo-active area of CSIPs (wavelength of 14.7 ¿m) induce intensified near fields for the intersubband transition in a GaAs quantum well at 100 nm below the metal/substrate interface. Cross-hole arrays yield the highest efficiency of 7%, which is by a factor of about four higher than the previously achieved value with square patch arrays.