Quantum grid infrared photodetectors

In this letter we introduce a quantum well infrared photodetector (QWIP) st ructure, which we refer to as the quantum grid infrared photodetector (QGIP ). In an ideal structure, a grid pattern with very narrow linewidth is crea ted in the QWIP active region to achieve lateral electron confinement, ther eby improving its absorption as well as transport characteristics. In order to realize this detector structure, we have fabricated QGIPs with line pat terns of lithographical linewidths w(l) ranging from 0.1 to 4 mu m, allowin g for possible sidewall depletion. Low-damage reactive ion beam etching was employed to produce vertical sidewalls. From the experimental data, althou gh the best detector performance occurs at w(l)approximate to 1.5 mu m, the detector starts to improve when w(l)<0.5 mu m, indicating a possible quant um confinement effect. (C) 1999 American Institute of Physics. [S0003-6951( 99)04005-X].