Effect of performances on structural differences of VIS-SWIR photodetectors for multispectral imaging and sensing

Solid-state imaging devices, commonly found in cameras and scientific instruments, rely on charge-coupled device (CCD) technology. However, CCD photodetector arrays have constrained spectral range (< 1.0 μm) due to absorption characteristics of silicon (Si), and inadequate quantum efficiency (QE) over broad spectral ranges. To overcome these limitations, we propose a novel photodetector structure that enable broad spectral range detection, covering visible to shortwave infrared (VIS-SWIR) wavelength. This breakthrough detector achieves high QE (>90%) over wide spectral ranges and offers high frequency response >10 GHz. To address the challenge of absorption beyond the visible region, we utilize III-V compound semiconductor material as the absorption layer fabricated on matured InP substrates. The objective is to develop a monolithic photodiode and array that covers wavelengths from 400 nm to 1750 nm, with high frequency response (>8 GHz) and high QE. The use of matured substrates and III-V semiconductor materials simplifies manufacturing, improves spectral coverage, and enhances performance significantly compared to existing technologies. The photodiodes can be either top or bottom illuminated and feature a single set of absorption layers designed to achieve desired QE and speed. They can be used as single element or in an array configuration, with a metal line connection scheme enabling rapid and random addressing of individual pixels. Additionally, these uncooled photodiodes offer the advantage of performing reliably under various temperature variations. This detector holds great potential benefits for multispectral imaging, advanced communication systems, and sensing applications. We present characterization results of the fabricated test structures.