High-speed III-V based avalanche photodiodes for optical communications—the forefront and expanding applications

Abstract

Avalanche photodiodes (APDs), i.e., semiconductor devices, which convert and amplify optical signals into electrical signals, are used for optical communications and for imaging and medical applications. The major requirements for APDs in optical communications are high-speed operation for high data rates and high-sensitivity operation for extending the transmission reach. This paper overviews the achievements of high-speed APDs for 100-Gbit/s optical communications, focusing on III-V material systems, which are advantageous in terms of band engineering. The outlook for APDs in future optical communications is also described.

Silicon–germanium receivers for short-wave-infrared optoelectronics and communications

“…III-V compound semiconductors are, with their direct bandgap, the most mature materials for use in optically active devices. For photodetection, favorable features of III-V semiconductors are tailorable energy bandgaps, high absorption and high carrier drift velocities, as well as mature device designs and fabrication flows [55][56][57].…”

“…Photodiodes based on indium phosphide (InP), gallium arsenide (GaAs), indium gallium arsenide, and indium gallium arsenide phosphide are the standard bearers that have been in place for decades and dominate the markets. In the last years, integration of III-V hetero-structures with Si CMOS platforms [57,58] picked up steam, with chip-tochip bonding, direct hetero-epitaxy, or transfer printing methods used to that end [59][60][61][62]. Although such approaches would enable to benefit from both worlds, heterogeneous integration still faces severe challenges.…”

“…In parallel with advances in crystalline semiconductor photodetectors [39][40][41][42][43][44][45][46][47][51][52][53][54][55][56][57][58][59][60][61][62][63], new material classes and integration strategies were shown to have great potentials in integrated nanophotonics. Emerging photodetector designs include plasmonics [64][65][66][67][68][69] and two-dimensional (2D) materials such as graphene [70][71][72][73] or transition metal dichalcogenides [74][75][76][77][78][79], among others studied alternatives [80][81][82][83][84][85][86].…”

“…However, both type of devices suffer from high dark currents, jeopardizing future opto-electrical performance improvements. While noise is lower, the gain-bandwidth product is higher and, in general, performances are better with SACM devices [154][155][156]159], they are driven with overly high voltages (>20 V) [154][155][156] that are comparable to bias levels needed for III-V-based devices [55][56][57][58]. Such excessively high voltage driving is not practical for many energy-aware applications, however [181] (Figure 7).…”

Silicon-Germanium Avalanche Receivers With fJ/bit Energy Consumption

“…In contrast, intensity-modulation and direct detection (IM-DD) receivers are preferred in short-distance connections, because of their simplicity [11]. Mainstream receivers are based on III/V [19,20] or silicon-germanium (Si-Ge) photodiodes [21]. They are then used together with an additional electronic circuitry with trans-impendence (TIA), limiting (LA) or gain-controlled (GCA) amplifiers.…”