Guided-mode resonance enhanced mid-infrared photodetectors
To leverage appealing applications in mid-infrared wavelength, photodetectors with high-performance, both optically and electrically, are desired. Majority of this thesis discusses guided-mode resonance enhanced mid-wave infrared (MWIR, 3 − 5 μm photodetectors. Chapter 1 gives a brief overview on type-II superlattice infrared photodetectors (T2SL), guided-mode resonance (GMR) and highly-doped semiconductors (n⁺⁺). We then discuss leveraging n⁺⁺ for GMR enhancement in T2SLs in an all-epitaxial design. In Chapter 2, we demonstrate a GMR enhanced MWIR detector at T = 79 K. In chapter 3, we further optimize our GMR photodetector design and demonstrate a high-operating temperature (HOT) GMR photodetector with over an order enhancement in external-quantum efficiencies (EQE) and over 4 × 10¹⁰ cm√Hz/ specific detectivity, D* in an ultra-thin absorber only 250 nm thick. Chapter 4, we investigate and optimize GMR photodetectors further to achieve room-temperature operation (RT) at low operating biases with about an order enhancement in EQE with D* > 1 × 10¹⁰ cm√Hz/, a superior value compared to state-of-art III-V photodetectors. In chapter 5, to show potential integration in focal-plane arrays, we integrate RT GMR photodetectors in flipchip configuration and demonstrate enhanced response in backside illuminated GMR photodetectors at room-temperatures. Apart from our research in GMR MWIR photodetectors, this thesis also discusses long-wave infrared (LWIR,8 − 13 μm) topological phonon chain in Chapter 6. In this chapter, we model bi-periodic chain of AlN pillars with subwavelength diameter and show through surface phonon coupling, the AlN chain can support edge-mode (an important parameter in topological insulators). We further study fabricated and grown chains of AlN pillars through reflection measurements. Finally, we summarize the thesis with a conclusion in chapter 7.