Dark current analysis in high-speed germanium p-i-n waveguide photodetectors

Abstract

We present a dark current analysis in waveguide-coupled germanium vertical p-i-n photodetectors. In the analysis, surface leakage current and bulk leakage current were separated, and their activation energies were extracted. Surface leakage current originating from the minority carrier generation on the Ge layer sidewalls, governed by the Shockley-Read-Hall process and enhanced by the trap-assisted-tunneling process, was identified as the main contribution to the dark current of vertical p-i-n photodiodes at room temperature. The behavior of this surface leakage current as a function of temperature and (reverse bias) voltage is well reproduced by using the Hurckx model for trap-assisted-tunneling.

Direct Nanoscale Characterization of Deep Levels in AgCuInGaSe2 Using Electron Energy‐Loss Spectroscopy in the Scanning Transmission Electron Microscope

“…2019, 9,1901612 (hole) trap signal peaked at about 270 K. The trap energy, extracted via Arrhenius analysis of spectra from a range of different rate windows (as shown in the Figure 2a, inset), was found to be E T = E V + 0.56 eV, or lying within the bandgap and 0.56 eV above the valence band maximum. These data were collected at a 0.8 s −1 rate window across a 150-300 K temperature range and reveal a single majority carrier Adv.…”

“…2019, 9,1901612 Table 1 presents average compositional fractions, along with associated standard deviations as conservative estimates of uncertainty, for each of the relevant elements (and combinations of elements) in both normal and defect regions. Energy Mater.…”

Comprehensive Study on Chip-Integrated Germanium Pin Photodetectors for Energy-Efficient Silicon Interconnects

“…Since the first successful implementation of this concept by Ahn, et al, a large number of architectures have been proposed and experimentally demonstrated. Ge homo-junction [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] and Si-Ge-Si heterojunction [32,[35][36][37][38][39][40] photodetector arrangements have notably been evaluated. Both types of devices consist in pin junction arrangements, with a light absorption occurring in the intrinsic regions.…”

“…This results in slower responses, reduced photo-responsivities, and higher dark-currents in homo-junction structures [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. In contrast, heterostructured Ge photodetectors with full Si via-contacts and doping scheme avoid Ge processing issues and might substantially simplify the process flow [32,[35][36][37][38][39][40]. For example, the same masking, ion implantation, and metal contacting steps can be used for the fabrication of active optical link components such as Si modulators and Si-Ge-Si photodetectors [41].…”

“…This architecture also leads to the flexible control of the light confinement in the intrinsic region. Such photodetectors have been realized and demonstrated with significantly improved performances in near-IR wavelengths [32,[35][36][37][38][39][40]. In this work, we comprehensively investigate the properties of optical photodetectors with lateral Si-Ge-Si heterojunctions.…”