Optimization of blazed quantum-grid infrared photodetectors

In a quantum-grid infrared photodetector (QGIP), the active multiple quantum well material is patterned into a grid structure. The purposes of the grid are, on the one hand, to create additional lateral electron confinement and, on the other, to convert part of the incident light into parallel propagation. With these two unique functions, a QGIP allows intersubband transition to occur in all directions. In this work, we focused on improving the effectiveness of a QGIP in redirecting the propagation of light using a blazed 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 structure, the sensitivity of a QGIP can be improved by a factor of 1.8 compared with a regular QGIP with rectangular profiles. (C) 1999 American Institute of Physics. [S0003-6951(99)02049-5].