Low dark current lateral Ge PIN photodetector array with resonant cavity effect for short wave infrared imaging

Abstract

High-performance Germanium (Ge) lateral PIN photodetector (PD) arrays for short wave infrared (SWIR) imaging based on Ge-on-insulator (GOI) platform was proposed and demonstrated. The high-quality GOI platform with top-Ge layer thickness of 1.25 μm and threading dislocation density of less than 105 cm-2 was prepared by using bonding and smart-cut technology. P-type and N-type regions with centrosymmetric racetrack shapes were introduced to lower the sidewall electric field and suppress the surface leakage current of the PD. Benefiting from the high-quality of the GOI platform and the unique design of lateral active regions, a low dark current of 2 nA under -1 V with outstanding rectification ratio of 2.1×106 were obtained at room temperature. Through constructing a vertical resonant cavity by SiO2 passivation layer and the Si/SiO2 substrate, the responsivity at 1550 nm was enhanced to 0.46 A/W with a high specific detectivity of 3.09×1010 Jones under -1 V. Ultimately, SWIR imaging was demonstrated by a Ge lateral PIN PD line array with 1×8 pixels under zero bias at room temperature. The results indicate that the proposed lateral Ge PD structure holds great application potential in the field of SWIR imaging.

Photoresponse of Carbon Nanofiber-Based Photodetector and Its Enhancement on CuNi Nanoparticle Adsorption

“…There are three key figures of merit of a photodetector: , (i) the responsivity R , a measure of the sensitivity of the photodetector and given by R ( λ ) = J ( λ ) / P ( λ ) with J = I / A D being the photocurrent density determined using the photocurrent I and the device area A D , and P being the incident optical power density; (ii) the detectivity D , that measures the capacity of the photodetector to detect weak output signals and is estimated using ,− D ( λ ) = R ( λ ) × A normalD 1 / 2 false( 2 q I normald false) 1 / 2 and (iii) the gain G , a measure of the number of generated electrons per photon and given by − G = R h · c q · λ where q , h , and c are the electronic charge, Planck constant, and light speed, respectively. The formula used here for D is based on the assumption that the dominant contribution to the detector noise comes from the shot noise, which is parametrized in I d .…”