High-performance, tensile-strained Ge p-i-n photodetectors on a Si platform

Abstract

We demonstrate a high-performance, tensile-strained Ge p-i-n photodetector on Si platform with an extended detection spectrum of 650–1605 nm and a 3 dB bandwidth of 8.5 GHz measured at λ=1040nm. The full bandwidth of the photodetector is achieved at a low reverse bias of 1 V, compatible with the low driving voltage requirements of Si ultralarge-scale integrated circuits. Due to the direct bandgap shrinkage induced by a 0.20% tensile strain in the Ge layer, the device covers the entire C band and a large part of the L band in telecommunications. The responsivities of the device at 850, 980, 1310, 1550, and 1605 nm are 0.55, 0.68, 0.87, 0.56, and 0.11A∕W, respectively, without antireflection coating. The internal quantum efficiency in the wavelength range of 650–1340 nm is over 90%. The entire device was fabricated using materials and processing that can be implemented in a standard Si complementary metal oxide semiconductor (CMOS) process flow. With high speed, a broad detection spectrum and compatibility with Si CMOS technology, this device is attractive for applications in both telecommunications and integrated optical interconnects.

Ge-on-Si photonic devices for photonic-electronic integration on a Si platform

“…Due to the reduction of threading dislocation density by the post-growth annealing, the dark leakage current is reduced to ∼20 mA/cm 2 at the reverse bias of 1 V. As summarized in Fig. 8(c), the dark leakage current tends to decrease with decreasing the threading dislocation density in Ge [23,30,31,32,33]. However, the high-temperature annealing to reduce the dislocation density could be eliminated from the viewpoint of compatibility with the CMOS process for electronic circuits, otherwise Ge layers need to be formed at the beginning of front-end process, causing a drastic change in the existing CMOS process.…”

“…It is noted that a tensile strain is induced in Ge grown on Si (or SOI) wafers [22,23,24,25]. As in Fig.…”

“…A high-efficiency photodetection is realized in the C band (1.53-1.56 µm). Resulting from the bandgap narrowing due to the tensile strain in Ge, a red shift takes place in the responsivity spectrum, leading to a photodetection even in the L band (1.56-1.62 µm) [22,23,24,25]. Ge photodetectors integrated with Si WGs, shown in Fig.…”

Silicon-Germanium multi-quantum well photodetectors in the near infrared

“…Epitaxial germanium on silicon for photodetection by graded buffer layers [6,7], molecular beam epitaxy [8], a two-step growth by ultra-high vacuum chemical vapor deposition (UHVCVD) [9,10], and cyclic thermal annealing to reduce dislocation density in grown films were reported [11][12][13]. Metal-semiconductor-metal (MSM) and p-i-n type optical detectors were previously fabricated on blanket [3], and selective area grown germanium on silicon by MHAH technique are also reported earlier [5].…”

Germanium-on-SOI Infrared Detectors for Integrated Photonic Applications

“…20 show that this structure has little prospect for achieving efficiencies much greater than 10% at λ = 1550 nm. Despite the fact that our model does not include strain effects that can improve absorption at longer wavelengths [54], alternative geometries may still have to be utilized for optimal operation at 1550 nm. Recently, very promising results have been obtained by Dosunmu et al [55], who demonstrated Geon-SOI Schottky detectors with η = 59% at λ = 1550 nm, and bandwidths as high as 12 GHz.…”