Optimization of blazed quantum-grid infrared photodetectors

In a quantum-grid infrared photodetector (QGIP), the active multiple quantu m well material is patterned into a grid structure. The purposes of the gri d are, on the one hand, to create additional lateral electron confinement a nd, on the other, to convert part of the incident light into parallel propa gation. With these two unique functions, a QGIP allows intersubband transit ion to occur in all directions. In this work, we focused on improving the e ffectiveness of a QGIP in redirecting the propagation of light using a blaz ed structure. The optimization of the grid parameters in terms of the blaze angle and the periodicity was performed by numerical simulation using the modal transmission-line theory and verified by experiment. With a blazed st ructure, the sensitivity of a QGIP can be improved by a factor of 1.8 compa red with a regular QGIP with rectangular profiles. (C) 1999 American Instit ute of Physics. [S0003-6951(99)02049-5].