Resonant-cavity-enhanced mid-infrared photodetector on a silicon platform

Abstract

In this paper, we demonstrate high optical quantum efficiency (90%) resonant-cavity-enhanced mid-infrared photodetectors fabricated monolithically on a silicon platform. High quality photoconductive polycrystalline PbTe film is thermally evaporated, oxygen-sensitized at room temperature and acts as the infrared absorber. The cavity-enhanced detector operates in the critical coupling regime and shows a peak responsivity of 100 V/W at the resonant wavelength of 3.5 microm, 13.4 times higher compared to blanket PbTe film of the same thickness. Detectivity as high as 0.72 x 10(9) cmHz(1/2)W(-1) has been measured, comparable with commercial polycrystalline mid-infrared photodetectors. As low temperature processing (< 160 degrees C) is implemented in the entire fabrication process, our detector is promising for monolithic integration with Si readout integrated circuits.

Mid-infrared integrated photonics on silicon: a perspective

“…In particular, polycrystalline lead salts represent an attractive option for monolithic on-chip mid-IR detector integration up to 5 μm. They can be deposited on Si in a non-epitaxial manner via thermal evaporation or solution processing [186][187][188]. They also epitomize a class of semiconductors whose polycrystalline form rivals or even outperforms their single crystalline counterparts for IR detection, a unique feature owing to spatial separation of charge carriers near grain boundaries and hence long photo-carrier lifetime [189,190].…”

Integrated photonics for infrared spectroscopic sensing

“…Unlike other narrow-bandgap semiconductors which mandate epitaxially grown single crystals for device fabrication, the polycrystalline form of these chalcogenide semiconductors offer performance comparable or even superior compared to their single-crystalline counterparts due to a unique charge-separating mechanism at grain boundaries [48][49][50][51]. These polycrystalline chalcogenides can be readily deposited via chemical bath deposition [52,53] or thermal evaporation, facilitating monolithic integration of active mid-IR photonic devices on common semiconductor or dielectric substrates [54][55][56]. Our previous work has developed deposition and processing of these chalcogenide materials and fabrication protocols of photonic devices operating at near-IR telecommunication wave bands on silicon as well as unconventional substrates such as polymers [57][58][59][60][61][62][63][64][65][66][67][68].…”

“…A PbTe layer is deposited first, followed by a 300 nm thick Sn contact layer with the Ge23Sb7S70 (GeSbS) waveguide layer on top. We choose chalcogenide glass as the waveguide material given its superior chemical stability and compatibility with PbTe materials [56]. The structure of the waveguide-integrated detector chip is illustrated in Figure 6b.…”

Molecular beam epitaxy and characterizations of PbTe grown on GaAs(211) substrates using CdTe/ZnTe buffers

“…For example, PbTe mid-infrared photovoltaic devices have been fabricated by using epitaxial PbTe on silicon substrates with BaF 2 /CaF 2 buffer layers. However, difficulty lies in manufacturing readout IC in this method as BaF 2 and CaF 2 are both deliquescent and fragile insulators [8][9][10][11]. Furthermore, the big differences of both lattice constant and thermal expansion coefficients between Si and PbTe lead to the formation of high density dislocations involved in the mid-infrared (MIR) detectors, and also lead to the glide of dislocations along the {100} planes by relieving thermal-misfit strain when temperature varies which make the detector instable [4][5][6].…”