On the route towards Si-based optical interconnects (original) (raw)

Progress in the field of integrated optoelectronics based on porous silicon

Thin Solid Films, 1997

Aluminum-porous silicon (Al-PS) Schottky junctions have demonstrated to be promising candidates for stable, wide band emission, silicon based light sources. Aluminum top contacts are defined by transforming the Al layer between different pads into anodic alumina (Al 2 O 3).The light emitted by the devices arises from the border of the metallic contact through the transparent and insulating alumina. With the aim of obtaining a higher external efficiency, different shapes for the aluminum top contact have been designed and characterised. The layout of the masks used in photolithography has been designed having in mind two possible applications for the light source: (1) as a silicon technologycompatible light source to be used for optical interconnections within VLSI-IC, and (2) as a pixel for 1D and 2D electroluminescent panels. An increase of external quantum efficiency due to increase of perimeter/area ratio has been demonstrated. Furthermore, the detection of the light emitted from the junction by means of a porous silicon photodetector integrated on the same chip is presented. Fabricated devices are characterised by means of electrical and optoelectronic techniques. q Elsevier Science S.A.

Amorphous silicon sensors for oxidised porous silicon optical waveguides buried in silicon wafers

Journal of Non-Crystalline Solids, 1998

We have developed an original technology to fabricate channel waveguides on monocrystalline silicon wafers, consisting of selective anodization followed by thermal processing. The obtained oxidised porous silicon waveguides show waveguiding properties, moreover, due to the fabrication process, the waveguides are placed just under the surface of the silicon wafer. A hydrogenated amorphous silicon film has been grown on top of the waveguide by a low temperature process, then Ž. aluminum contacts have been formed by standard lithography. Different device structures photodiodes and photoresistors are presented. Currentrvoltage properties in the dark and under light excitation accompanied with capacitancervoltage measurements have been used to develop a band diagram model.

Optical performance of hybrid porous silicon–porous alumina multilayers

Journal of Applied Physics, 2018

In this work, we study the optical response of structures involving porous silicon and porous alumina in a multi-layered hybrid structure. We performed a rational design of the optimal sequence necessary to produce a high transmission and selective filter, with potential applications in chemical and biosensors. The combination of these porous materials can be used to exploit its distinguishing features, i.e., high transparency of alumina and high refractive index of porous silicon. We assembled hybrid microcavities with a central porous alumina layer between two porous silicon Bragg reflectors. In this way, we constructed a Fabry-Perot resonator with high reflectivity and low absorption that improves the quality of the filter compared to a microcavity built only with porous silicon or porous alumina. We explored a simpler design in which one of the Bragg reflectors is replaced by the aluminium that remains bound to the alumina after its fabrication. We theoretically explored the potential of the proposal and its limitations when considering the roughness of the layers. We found that the quality of a microcavity made entirely with porous silicon shows a limit in the visible range due to light absorption. This limitation is overcome in the hybrid scheme, with the roughness of the layers determining the ultimate quality. Q-factors of 220 are experimentally obtained for microcavities supported on aluminium, while Q-factors around 600 are reached for microcavities with double Bragg reflectors, centred at 560 nm. This represents a four-fold increase with respect to the optimal porous silicon microcavity at this wavelength.

Recent progress in integrated waveguides based on oxidized porous silicon

Optical Materials, 2005

In this work we report the latest improvements in integrated optical waveguides based on oxidized porous silicon. Remarkably low propagation loss of 0.2 dB/cm in the visible is demonstrated. Straight waveguides of 1-10 cm long were fabricated in N +-type silicon substrates. Thickness of core region of all fabricated waveguides was of 8 lm while thickness of cladding layer was of 0.8, 1.5, and 2.5 lm. Optical loss in the visible and IR were measured by original method utilizing the 90°vertical bending at the waveguides endings which is a unique property of our waveguides. Significant improvement of the waveguide characteristics was obtained by optimizing the technological process: (a) eliminating the negative effect of swirl defects on uniformity of porous silicon layers; (b) developing the anodization regimes allowing the careful control of the porosity through the porous silicon thickness; (c) using silica mask instead of silicon nitride mask.

Fabrication and Characterization of Photodetector Based on Porous Silicon

e-Journal of Surface Science and Nanotechnology, 2010

Electrical and photoresponse properties of Al/porous silicon/crystalline Silicon/Al structure (Al/pSi/c-Si/Al) were investigated. Unoxidized porous Si layer was made on single crystalline p-Si using anodic etching in aqueous HF at a current density of 60 mA/cm 2 for 20 min etching time. The structure of porous layer was investigated using SEM and FTIR. The electrical properties of the Al/pSi/c-Si/Al junction were studied using dark I-V , illuminated I-V and C-V measurements. The rise time of the detector was found to be 100 ns and its resposnsivity was 0.38 A/W at 600 nm and 0.44 A/W at 800 nm when the photodetector bias is at −3 V.

Thermal management and optical entrapment in multilayered porous silicon for use as waveguide

Intelligent systems rely heavily on sensors and energy storage devices. Materials used in these devices are being upgraded using a variety of solid-state, chemical, and micro-machining techniques. Silicon, despite having an indirect bandgap, is being used in photonics due to technological advancements in device fabrication. Si photonics are in high demand due to their abundance and compatibility with CMOS. However, with reduced chip size, the thermal management is an important aspect which needs to be taken care. Multilayered Porous Silicon (PS) nanostructures were synthesized electrochemically. A 20-period Fabry Perrot Interference filter (FPIF) and Distributed Bragg Reflector (DBR) made from porous silicon showed optical entrapment beneficial for waveguides.

Optoelectronics silicon on insulator integrated circuits by porous silicon technology

ROMOPTO 2000: Sixth Conference on Optics, 2001

This work has been a team effort. The successful completion of this thesis was made possible through the generous support of Dr. Karl D. Hirschman, who not only provided the necessary vision and direction but also continuously gave encouragement and moral support. I would also like to thank Mr. Kevin Witt project sponsor through Semitool Inc. without which the project would have never gone forward. I also would like to express my gratitude to Joshua D. Winans; he was literally the backbone of the entire project by not only providing valuable ideas but also providing SEM images which are a very integral part of this thesis. Furthermore, I would like to thank my colleagues Shaoting Hu, Daiji Kawamura, Andrew McCabe and Chris Shea for their contributions and support. I would like to thank especially Patricia Meller for providing process support whenever needed. The completion of this project would not be possible without the generous support of the Semiconductor and Microsystems Fabrication Laboratory (SMFL) staff: Sean

Visible light from aluminum-porous silicon Schottky junctions

Thin Solid Films, 1996

The fabrication technologies and the properties of light-emitting devices based on A 1-porous silicon (PS) Schottky junctions have been developed. Bright light emission, visible by the naked eye at normal daylight, is observed at the edge of the electrodes under reverse bias. The electroluminescence (EL) starting voltage is in the range 5-18 V, depending on the doping level of Si substrate. The current level at which the EL starts is around 1 mA for devices of 2.3 X 10 " 3 cm 2 area. The lighi emission intensity increases with increasing current density. EL spectra were broad, covering the whole visible range. The time stability was excellent for all tested devices; the EL intensity did not show remarkable changes, even after more than ten days of continuous light emission at voltages lower than thermal breakdown.

Optical link for digital transmissions using porous silicon light emitting diode

Journal of Non-crystalline Solids, 2000

In this paper we present the frequency response of a stable Schottky (Al-porous silicon) light emitting device, under a high frequency sinusoidal driving signal. The ®rst silicon emitter±photodetector coupling, through a plastic ®ber was produced and the output signal was measured. The optical link which was used opens the possibility to analyze the application of such emitting device in logical transmission. Ó

All Si-based optical interconnect for interchip signal transmission

IEEE Photonics Technology Letters, 2003

Barrier to the commercial implementation of optical interconnects between integrated circuits (ICs) center around the fabrication of optical elements on wafers through conventional Si processes. Most other approaches for optical interconnects use direct bandgap emitters that require drastic changes in conventional fabrication processes. In this work, we demonstrate the ability to transmit electrical signals using Si-based components, i.e., the light was generated by biasing a p-n junction at avalanche breakdown voltage, light was coupled through a fiber cable made of SiO 2 , and detected by an Si-based avalanche photodiode. Results presented demonstrate the switching behavior of light emitter, transmission of signal across the fiber, and measurement of signal limited by the bandwidth of the receiver amplifier.