High Performance p-i-n Photodetectors on Ge-on-Insulator Platform

Area of Science:

• Optoelectronics
• Semiconductor Devices
• Materials Science

Background:

• Germanium-on-insulator (GOI) technology offers potential for advanced photodetector (PD) integration.
• Silicon-based photodetectors face limitations in performance and integration density.
• Improving dark current and responsivity in GOI PDs is crucial for next-generation optoelectronics.

Purpose of the Study:

• To demonstrate novel methods for enhancing the performance of p-i-n photodetectors (PDs) fabricated on germanium-on-insulator (GOI) substrates.
• To investigate the impact of defect layer removal on dark current characteristics.
• To explore strategies for improving optical performance through material integration.

Main Methods:

• Fabrication of p-i-n photodetectors on GOI substrates with careful removal of the initial germanium growth layer.
• Characterization of dark current, leakage current density, and responsivity at various wavelengths.
• Integration of a tetraethylorthorthosilicate (TEOS) layer to enhance optical confinement and resonant cavity effects.

Main Results:

• GOI photodetectors exhibited a dark current of 2.5 nA at -1 V, a 2.6-fold reduction compared to germanium PDs on silicon substrates.
• Achieved low bulk and surface leakage current densities of 1.79 mA/cm² and 0.34 μA/cm, respectively.
• Demonstrated responsivity of 0.5 A/W at 1550 nm and 0.9 A/W at 1310 nm, further enhanced by TEOS integration.

Conclusions:

• The developed methods significantly improve the performance of GOI photodetectors, particularly reducing dark current.
• TEOS layer integration enhances optical performance through improved confinement and resonance.
• These high-performance, CMOS-compatible GOI PDs are promising for telecommunications and monolithic optoelectronic integration.