Free carrier absorption in silicon

Uncooled infrared (IR) photodetectors for telecommunications, optical processor interconnects, and focal plane arrays are advantageously integrated into systems that are silicon based through advanced thin-film technologies. This paper reviews challenges of materials, microstructures, interfaces, and reactions of thin-film materials and technologies posed by such applications.

Proceedings, 2018

Integrated silicon photonics in the mid-infrared is a promising platform for cheap and miniaturized chemical sensors, including gas and/or liquid sensors for environmental monitoring and the consumer electronics market. One major challenge in integrated photonics is the design of an integrated detector sensitive enough to detect minimal changes in light intensity resulting from, for example, the absorption by the analyte. Further complexity arises from the need to fabricate such detectors at a high throughput with high requirements on fabrication tolerances. Here we analyze and compare the sensitivity of three different chip-integrated detectors at a wavelength of 4.17 µm, namely a resistance temperature detector (RTD), a diode and a vertical-cavity enhanced resonant detector (VERD).

Optica, 2014

Silicon photonics has recently been proposed for a diverse set of applications at mid-infrared wavelengths 1, 2 , the implementation of which require on-chip photodetectors. In planar geometries, dopant-based extrinsic photoconductors have long been used for mid-infrared detection with Si and Ge acting as host materials 3. Leveraging the dopant-induced sub-bandgap trap-states used in bulk photoconductors for waveguide integrated mid-infrared detectors offers simple processing, integration, and operation throughout the mid-infrared by appropriate choice of dopant (Fig. 1a). In particular, Si doped with Zn forms two trap levels ≈ 0.3 eV and ≈ 0.58 eV above the valence band 4-6 , and has been utilized extensively for cryogenically cooled bulk extrinsic photoconductors 3, 7. In this letter, we present room temperature operation of Zn + implanted Si waveguide photodiodes (Figs. 1b,c) from 2.2 µm to 2.4 µm, with measured responsivities of up to 87 ± 29 mA/W and low dark currents of < 10μA. While a number of Si waveguide (SiWG) integrated optoelectronic devices have been demonstrated in this wavelength range 8, 9 , efficient photodetection remains an important and challenging task. Thus, spectral translation of mid-infrared signals to the telecom regime via four-wave mixing in SiWGs has been proposed for on-chip detection 10 , which makes use of the sensitive integrated photodiodes (PDs) in the telecommunications wavelength range 11. However, this method requires a high-powered pump laser and long, on-chip-waveguide lengths to achieve efficient wavelength conversion. In addition, heterogeneous integration of both narrow-bandgap semiconductors 9,12-14 and graphene 15,16 with SiWGs has been demonstrated for on-chip mid-infrared detection. Though viable PDs have been demonstrated,

Journal of Applied Physics, 2013

A normal-incidence light-trapping scheme relying on black silicon surface nanostructures for Si-based photoemissive detectors, operating in the IR spectral range, is proposed. An absorptance enhancement by a factor of 2-3 is demonstrated for technologically most relevant, ultrathin (2 nm-3 nm) PtSi rear layers on Si. It is shown that this increase can be translated into an equivalent increase in responsivity because of the absorption limitation of detector performance. Pd 2 Si/p-Si detectors with black silicon are suggested as promising candidates for room temperature detection in the third optical window with an expected external quantum efficiency in the range of 9%-14%. V C 2013 AIP Publishing LLC. [http://dx.

IEEE Transactions on Electron Devices, 2000

Applied Physics Letters, 2006

A p-type Si homojunction detector responding in both near-and very-long-wavelength-infrared ͑NIR and VLWIR͒ ranges is demonstrated. The detector consists of a p ++-Si top contact layer, a p +-Si emitter, an undoped Si barrier, and a p ++-Si bottom contact layer grown on a Si substrate. Interband and intraband transitions lead to NIR and VLWIR responses, respectively. The responsivity, quantum efficiency, and detectivity at −1 V bias and 4.6 K are ϳ0.024 A / W, 3.7%, and ϳ1.7ϫ 10 9 cm Hz 1/2 / W at 0.8 m, while they are 1.8 A / W, 8.8%, and ϳ1.2 ϫ 10 11 cm Hz 1/2 / W at 25 m, respectively. The background limited infrared performance temperature at ±0.9 V bias is 25 K.

IEEE Transactions on Electron Devices, 1999

A detailed investigation of the near infrared detection process of an hydrogenated amorphous silicon sensor is presented. Single junction devices with micro-compensated absorber layer show photocurrent response to radiation up to 2 m at room temperature. This sensitivity is ascribed to both the high number of trap states existing in the absorber material and to the electric field distribution in the device.

An enhancement of the infrared detection efficiency of Si photon-counting detectors by inclusion of SiGe absorbing layers has been demonstrated for what is believed to be the first time. An improvement of 30 times in detection efficiency at a wavelength of 1210 nm compared with that of an all-Si structure operated under identical conditions has been measured. The Si͞Si 0.7 Ge 0.3 device is capable of room-temperature operation and has a response time of less than 300 ps.

Optical Components and Materials V, 2008

At the present time, silicon and InGaAs/InP photodetectors from different manufactures have rather low level of noise, a good uniformity of the surface response as well as a wide dynamic range and linearity. For these reasons they are exploited in the instruments for measuring optical radiation within the near infrared range 800-1600 nm. Furthermore, the silicon and InGaAs/InP photodetectors are used for maintaining the scales of spectral responsitivity in the above-listed spectral range in many laboratories. Due to the last application, we presented our studies of the reflectance and the internal quantum efficiency inherent in silicon and InGaAs/InP photodiodes from different manufactures.

SPIE Proceedings, 2008

At the present time, silicon and InGaAs/InP photodetectors from different manufactures have rather low level of noise, a good uniformity of the surface response as well as a wide dynamic range and linearity. For these reasons they are exploited in the instruments for measuring optical radiation within the near infrared range 800-1600 nm. Furthermore, the silicon and InGaAs/InP photodetectors are used for maintaining the scales of spectral responsitivity in the above-listed spectral range in many laboratories. Due to the last application, we presented our studies of the reflectance and the internal quantum efficiency inherent in silicon and InGaAs/InP photodiodes from different manufactures.