Spectrally Selective Ultrathin Photodetectors Using Strong Interference in Nanocavity Design

Abstract

Thinning the active layer's thickness of the semiconductor down to a level comparable with the carriers' diffusion length while keeping its absorption high is an ultimate goal to boost the performance of optoelectronic devices. Strong interference in multilayer structures is one of the promising and practical solutions owing to their simple and large-scale compatible fabrication route. These nanocavity designs not only provide near unity absorption, but they can also be designed in a way that a spectrally selective absorption response can be achieved. In this letter, we will demonstrate the functionality of a metalinsulator-semiconductor (MIS) cavity to obtain spectrally selective ultrathin photodetectors. To prove our theoretical and numerical findings, a 4-nm-thick amorphous silicon (a-Si)-based MIS cavity is designed, fabricated, and characterized. The experimental results show that the optimized cavity design can act as an efficient visible blind ultraviolet (UV) photodetector. The proposed design shows the responsivity values of 120 and 2.5 mA/W in the UV (λ = 350 nm) and visible (λ = 500 nm) regions, respectively.

Highly Efficient Semiconductor-Based Metasurface for Photoelectrochemical Water Splitting: Broadband Light Perfect Absorption with Dimensions Smaller than the Diffusion Length

“…These devices are ideally designed to perfectly absorb and harvest light in a narrow or broad frequency range [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. These perfect metamaterial absorbers have a wide range of applications including sensing [24][25][26], filtering [27,28], coherent emission [29][30][31][32], photovoltaics and thermal photovoltaics [33][34][35][36][37][38], photodetection [39][40][41], solar vapor generation [42], and photochemistry [43][44][45]. Among these applications, photochemistry and photoelectrochemical water splitting has become a promising technology to supply the future clean energy demand, and it is thought to be the "holy grail" of energy conversion and storage revolution.…”

Ultra-broadband Near-Unity Light Absorption by Disjunct Scattering Resonances of Disordered Nanounits Created with Atomic Scale Shadowing Effect

“…Therefore, several lithography-free designs were fabricated recently to achieve near-unity light absorption in dimensions much smaller than the wavelength [6,8,. The strong light-matter interaction in this lithography-free planar design can be acquired through the strong interference in planar ultrathin designs [42][43][44][45]. However, a substantial enhancement in light absorption capability of a metamaterial design could be achieved via surface texturing.…”