Design and simulation of mid-infrared photodetectors

Abstract

Mid-wavelength infrared (MWIR) photodetectors with highest sensitivity wavelength at spectral windows of 3-5 μm have garnered significant attention due to the largest atmospheric transmission in this range. Conventional photodetectors performing in this wavelength range are predominantly focused on materials such as PbSnTe, InSb and HgCdTe. These materials have troubles in reproducible development of uniform composition of epitaxial layers and bulk crystals. It also requires a low-temperature condition that contributes to the creation of alternative material systems, such as InAsSb and InAs / GaSb type-II superlattice (SL) related material systems. A study to optimize surface plasmon polariton (SPP) was proposed in recent years to enhance the performance of photodetectors. By positioning a plasmonic structure with a strong light-focusing capability on the sub-wavelength regime, tight spatial confinement, near to a detector's absorption area and high local field-intensity of surface plasmons. Light-matter interaction can be enhanced. Hence, light detection performance increased. In this project, I utilized plasmonic enhancement technique without compromising response speed to enhance sensitivity. I have designed various metallic patch structures to foster the performance of InAs 0.91 Sb 0.09 -based heterojunction n-i-p photodiode. Utilizing finite-difference time-domain software (FDTD Solutions, Lumerical Inc), following simulation results indicate that using a metallic patch structures can certainly excite the obvious resonance within MWIR range. Hence, they can greatly enhance the electrical field, resulting in improved detection performance. The attribute enables the MWIR detector to function well under room temperature.