Spectrally resolved absolute measurements of hot-carrier-induced photon emission in silicon are reported. In order to avoid uncertainties in geometrical and physical parameters, the simplest conceivable device, an avalanching p-n junction, was used. A photon emission efficiency of 2.9*10/sup 5/ photons with energy higher than 1.14 eV per carrier crossing the junction, independent of the lattice temperature down to 20 K, was measured. On the basis of these results the bremsstrahlung origin of the hot-carrier-induced light emission is critically reviewed. >

On the bremsstrahlung origin of hot-carrier-induced photons in silicon devices

Integrated quantum photonic applications, providing physically guaranteed communications security, subshot-noise measurement, and tremendous computational power, are nearly within technological reach. Silicon as a technology platform has proven formidable in establishing the micro-electronics revolution, and it might do so again in the quantum technology revolution. Silicon has taken photonics by storm, with its promise of scalable manufacture, integration, and compatibility with CMOS microelectronics. These same properties, and a few others, motivate its use for large-scale quantum optics as well. In this paper, we provide context to the development of quantum optics in silicon. We review the development of the various components that constitute integrated quantum photonic systems, and we identify the challenges that must be faced and their potential solutions for silicon quantum photonics to make quantum technology a reality.

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Silicon Quantum Photonics

Silicon avalanche light-emitting devices (Si Av LEDs) offer various possibilities for realizing micro- and even nano- optical biosensors directly on chip. The light-emitting devices (LEDs) operate in the wavelength range of about 450-850nm, and their optical power emitted is of the order of a few hundreds of nW/µm2. These LEDs could be fabricated in micro- and nano- dimensions by using modern semiconductor fabrication processing technologies through the mainstream of silicon material. Through a series of experiments, the dispersion phenomena in the Si Av LED are observed. Also, its light emission point was proved to locate at about one micron just below the silicon-silicon oxide interface. Subsequently, a micro-fluidic channel sensor was designed by using the dispersion characteristics owned by the Si Av LED. The analytes flowing through a micro-fluidic channel could be studied by their specific transmittance and absorption spectra. Moreover, simulations verify that a novel designed waveguide-based sensor could be fabricated on chip between the Si optical source and the Si P-I-N detector.

Micro optical sensors based on avalanching silicon light-emitting devices monolithically integrated on chips

The physics of electron transport in bulk silicon is investigated by using a newly developed Monte Carlo simulator which improves the state‐of‐the‐art treatment of hot carrier transport. (1) The full band structure of the semiconductor was computed by using an empirical‐pseudopotential method. (2) A phonon dispersion curve was obtained from an adiabatic bond‐charge model. (3) Electron‐phonon scattering was computed by using a rigid pseudo‐ion model. The calculated scattering rate is consistent with the full band structure and the phonon dispersion curve of silicon, thus leaving no adjustable parameters such as deformation potential coefficients. (4) The impact‐ionization rate was calculated by using Fermi’s golden rule directly from the full band structure. We took into account the dielectric function depending on both wave vector and transition energy in the numerical calculation of the rate. The impact‐ionization rate obtained in the present study strongly depends on both wave vector and band index of the conduction electron, which is ignored by the traditional Keldysh formula. (5) In the simulator, the final state of a scattering electron is determined in such a way as to conserve both energy and momentum in scattering processes. The simulated results, under the steady‐state conditions as well as under the nonequilibrium conditions, are presented and compared with experimental results. Special attention is focused on anisotropic transport during velocity overshoot. Quantitative agreement between calculated and experimental results confirms the validity of the newly developed Monte Carlo simulator and the physical models that were used.

A Monte Carlo simulation of anisotropic electron transport in silicon including full band structure and anisotropic impact‐ionization model

One of the main issues of Single Photon Avalanche Diode arrays is optical crosstalk. Since its intensity increases with reducing the distance between devices, this phenomenon limits the density of integration within arrays. In the past optical crosstalk was ascribed essentially to the light propagating from one detector to another through direct optical paths. Accordingly, reflecting trenches between devices were proposed to prevent it, but they proved to be not completely effective. In this paper we will present experimental evidence that a significant contribution to optical crosstalk comes from light reflected internally off the bottom of the chip, thus being impossible to eliminate it completely by means of trenches. We will also propose an optical model to predict the dependence of crosstalk on the distance between devices.

Optical crosstalk in single photon avalanche diode arrays: a new complete model

There has been a renewed interest in the spectra of emitted light from Si metal-oxide-semiconductor field-effect transistors (MOSFET's) in the belief that a better understanding of this phenomenon will lead to a deeper understanding of hot carriers in these devices. In this paper, we attempt to explain the physical mechanisms responsible for the light emission in Si under varying doping and carrier conditions and as a function of hot-carrier distribution functions. Based on this study, we have found that a proper inclusion of a realistic band structure is essential for the study of hot-carrier luminescence in Si. Furthermore, by including these band-structure effects, we conclude that the dominant light-emission mechanism in normally biased Si MOSFET's is a combination of direct and phonon-assisted inter-conduction-band radiation.

Jeff Bude

Papers

Hot-carrier luminescence in Si