Resonant cavity enhanced quantum ring photodetector at 20,upmu m wavelength

In this paper, in order to enhance the performance characteristics of photodetector, an InAs/GaAs quantum ring infrared photodetector (QRIP) with resonant cavity structure is proposed. For this purpose, distributed bragg reflectors (DBR) in the bottom of structure are used to reflect the transmitted beam back into the active region. For further confinement of light in the active region, a gold layer is added to structure as top reflector and the performance of structures is compared with and without top reflector. Numerical simulation results show that using resonant cavity structure can improve quantum efficiency and responsivity of photodetector. Furthermore, the specific detectivity of device can increase about one order of magnitude using resonant cavity structure. Results show specific detectivity, $hbox {D}^{*}$ , about $sim $ 10 $^{11},(hbox {cm},hbox {Hz}^{1/2}hbox {/W})$ for conventional QRIP and $sim $ 10 $^{12},(hbox {cm},hbox {Hz}^{1/2}hbox {/W})$ for conventional QRIP embedded in resonant cavity. As a result of enhancement in detectivity, the operation temperature of detector can be increased up to about 150 K.