Dependence of Performance of Surface Plasmon Coupled Quantum Well Infrared Photodetectors on Doping

Three samples of Quantum Well Infrared Photodetectors (QWIPs) with different well doping were proposed for comparison between metallic grating and etched grating. All different doping samples with detectivity 1x10(11) cm*Hz(0.5)/W were achieved under 77 K with metallic grating and the highest detectivity was 2.92x10(11) cm*Hz(0.5)/W with 3.3E17 cm(-3) well doping. The metallic grating samples showed a different quantum efficiency (QE) increment behavior from the etched grating samples as we increased the well doping. The QE enhancement of metallic grating sample was smaller than that in positive bias due to the potential spike between the AlGaAs/GaAs interface. The metallic grating device is more sensitive to the extra barrier between the AlGaAs/GaAs interface because of a narrower coupling bandwidth of surface plasmon. Though the enhancement varied between different samples as we changed the well dopings, the detectivity could still be kept within a reasonable range, which is important for focal plane array applications.