High-speed lateral PIN photodiodes in silicon technologies

Abstract

High speed, efficient photodetectors are difficult to fabricate in standard silicon fabrication processes due to the long absorption length of silicon. However, high performance servers will soon require dense optical interconnects with low cost and high reliability, and this trend favors monolithic silicon receivers over hybrid counterparts. Recently, lateral PIN photodiode structures have been demonstrated in silicon CMOS technology with little or no process modifications. Optical receivers based on these detectors have achieved record performance in terms of speed and sensitivity. This paper will discuss the advantages, issues and recent advances in silicon-based photodetectors and optical receivers. This includes the fastest photodetector ever implemented in a standard bulk CMOS process, a 13.9 Gb/s lateral trench detector implemented in a modified EDRAM process, and a >15 GHz pure germanium photodiode grown directly on a silicon substrate.

Performance Assessment of Ge-on-SOI-photodetector / Si-CMOS Receivers for High-Speed Optical Communications

“…The lateral-trench detector geometry described in (9) consists of a thick SOI lateral p-i-n detector with deep trench electrodes that penetrate into most of the absorbing region above the SOI. When designed to minimize capacitance, these detectors can produce bandwidths over 10 GHz, with over 50% quantum efficiency (10). The waveguide detector geometry is another approach that decouples the absorption length and transport distance, and recent demonstrations of these devices on SOI (11) have produced devices with 8-GHz bandwidth and = 12%.…”

Designer germanium quantum dot phototransistor for near infrared optical detection and amplification

“…Phototransistors are a unique optical transducer in which light detection/photoelectric conversion (photodiodes) and electrical signal amplification (transistors) are combined within a single device and thus have none of the associated concerns of noise increments, high voltages and high cost [18][19][20]. Among the possible material and device structure choices for phototransistors, Ge MOS transistors offer promising solutions for low-cost, short-reach optical interconnects, thanks to Ge's high optical absorption coefficient and enhanced carrier mobility.…”

Photoresponses in Poly-Si Phototransistors Incorporating Germanium Quantum Dots in the Gate Dielectrics

“…These integrated devices are critical elements needed for development of low-cost and high-performance monolithic receiver for short reach and chip-to-chip interconnects. Phototransistors (PTs) are a type of optical transducer in which light detection and signal amplification are combined in a single device without the noise increment and high bias voltages associated with avalanche photodiodes [1] or lateral pi-n diode [2], and the high cost accompanied by vertical p-i-n detectors or germanium (Ge) on Si-on-insulator p-i-n devices [1,3]. In particular, PTs with planar structures such as thinfilm transistors (TFTs) are expected to be an essential component for a receiver in telecommunication systems due to the potential for large area integrated circuits.…”