Carrier Concentration In Silicon Research Articles

Recalculation of Intrinsic Carrier Concentration in Silicon at T = 300 K in Presence of Degenerate Doping

Recalculation of Intrinsic Carrier Concentration in Silicon at T = 300 K in Presence of Degenerate Doping

Flexoelectronic doping of degenerate silicon and correlated electron behavior

In metal/degenerately doped silicon bilayer structure, the interfacial flexoelectric effect due to strain gradient leads to charge carrier transfer from metal layer to the silicon layer. This excess charge carrier concentration is called flexoelectronic doping or flexoelectronic charge transfer, which gives rise to an electronically polarized (order of magnitude larger than ferroelectric materials) silicon layer. In the transport measurements, the charge carrier concentration in silicon is found to increase by two orders of magnitude due to flexoelectronic doping, which changes the Fermi level and the Hall response. The flexoelectronic charge accumulation modifies the electron-electron and the electron phonon coupling, which gives rise to Mott metal-insulator transition and magnetism of phonons, respectively. The coexistence of flexoelectronic polarization and magnetism gives rise to a new class of materials called electronic multiferroics. By controlling the flexoelectronic doping, material behavior can potentially be engineered for quantum, spintronics and electronics applications in semiconductor materials.

SPICE Modeling of Photoelectric Effects in Silicon With Generalized Devices

Modeling photoelectric effects in semiconductors with electrical simulators is demonstrated in typical 1-D and 2-D architectures. The concept is based on a coarse meshing of the semiconductor with the so-called generalized lumped devices, where equivalent voltages and currents are used in place of minority carrier excess concentrations and minority carrier gradients, respectively, and where the light-induced excess carrier concentration in silicon is introduced by means of internal current sources. Generation, propagation, and collection of these minority carriers are analyzed for different structures which can behave as photosensors or solar cells. Both static and transient operations are found in good agreement with TCAD numerical simulations while using the same physical and geometrical parameters.

Comprehensive description of the electro-optic effects in strained silicon waveguides

We present a novel and comprehensive analysis method that considers both the plasma-dispersion effect and the strain-induced Pockels effect to faithfully describe the electro-optic effects taking place in a strained silicon waveguide under an applied voltage. The change in carrier distribution arising from the application of a voltage leads to a redistribution of the electrostatic field which deeply affects the strain-induced Pockels effect. By simulating the strain gradient distribution inside the waveguide together with the free carrier concentration in silicon, we were able to describe that the effective index change due to the Pockels effect in strained silicon waveguides and the applied voltage have a nonlinear relationship.

Carrier concentration in silicon at recharge of the divacancy during the configurational reconstruction

Carrier concentration in silicon at recharge of the divacancy during the configurational reconstruction

Polarization-independent terahertz wave modulator based on graphene-silicon hybrid structure**Project supported by the National Natural Science Foundation of China (Grant No. 61565004), the Natural Science Foundation of Guangxi Zhuang Autonomous Region, China (Grant Nos. 2013GXNSFDA019002 and 2014GXNSFGA118003), the Guangxi Scientific Research and Technology Development Program, China (Grant No. 1598017-1), the Guilin Scientific Research and Technology Development Program, China (Grant Nos. 20140127-1

In this study, we propose and demonstrate a broadband polarization-independent terahertz modulator based on graphene/silicon hybrid structure through a combination of continuous wave optical illumination and electrical gating. Under a pump power of 400 mW and the voltages ranging from –1.8 V to 1.4 V, modulation depths in a range of –23%–62% are achieved in a frequency range from 0.25 THz to 0.65 THz. The modulator is also found to have a transition from unidirectional modulation to bidirectional modulation with the increase of pump power. Combining the Raman spectra and Schottky current–voltage characteristics of the device, it is found that the large amplitude modulation is ascribed to the electric-field controlled carrier concentration in silicon with assistance of the graphene electrode and Schottky junction.

Electrical properties of bio-SiC and Si components of the SiC/Si biomorphic composite

The electrical resistivity ρ of bio-SiC, a highly porous cellular material prepared from a biomorphic composite SiC/Si based on white eucalyptus wood through the chemical removal of silicon, was measured in the temperature range 5–100 K. The electrical resistivity of bio-SiC was found to be anisotropic along and across the cellular pores. The activation energy of charge transfer in bio-SiC was estimated. The measured values of ρ for the SiC/Si biomorphic composite and bio-SiC were used to determine the electrical resistivity ρ and the carrier concentration in silicon, which is one of the constituents of the composite.

Monitoring of the formation and removal of bulk, surface, and interfacial carrier traps on silicon(100)

An RF probe was used to monitor the steady-state photo-generated carrier concentration in silicon with and without an oxide layer. The changes in this steady-state concentration during exposure to gaseous molecular and atomic species such as He, H2, O2, H, and O at temperatures between 25 and 450 °C are interpreted in terms of changes in the bulk silicon, interface, and exposed surface. The initial experiments established the relationship between the carrier concentration and the RF-probe signal, and distinguished between changes in the bulk, and on silicon surfaces and interfaces. It was found that in the case of hydrogen, bulk passivation and depassivation by H2 can be observed only at elevated temperatures, with or without an oxide layer. H-atom depassivation can be observed at all temperatures and is irreversible at room temperature. The formation of an oxide layer by exposure to O atoms at 25 and 450 °C was followed, and the oxides formed were then treated in an attempt to create an SiO2/Si interface with an acceptable density of interfacial states.

Effect of trap location and trap-assisted Auger recombination on silicon solar cell performance

Model calculations were performed to investigate and quantify the effect of trap location and trap-assisted Auger recombination on silicon solar cell performance. Trap location has a significant influence on the lifetime behavior as a function of doping and injected carrier concentration in silicon. It Is shown in this paper that for a high quality silicon (/spl tau/=10 ms at 200 ohm-cm, no intentional doping), high resistivity (/spl ges/200 ohm-cm) is optimum for high efficiency one sun solar cells if the lifetime limiting trap is located near midgap. However, if the trap is shallow (E/sub t/-E/sub v//spl les/0.2 eV), the optimum resistivity shifts to about 0.2 ohm-cm. For a low quality silicon material or technology (10 /spl mu/s at 200 ohm-cm, prior to intentional doping) the optimum base resistivity for one sun solar cells is found to be /spl sim/0.2 ohm-cm, regardless of the trap location. It is shown that the presence of a shallow trap can significantly degrade the performance of a concentrator cell fabricated on high-resistivity high-lifetime silicon material because of an undesirable injection level dependence in the carrier lifetime. The effect of trap assisted Auger recombination on the cell performance has also been modelled in this paper. It is found that the trap-assisted Auger recombination does not influence the one sun cell performance appreciably, but can degrade the concentrator cell performance if the trap-assisted Auger recombination coefficient value exceeds 2/spl times/10/sup -14/ cm/sup 3//s. Therefore, it is necessary to know the starting lifetime as well as trap location in order to specify base resistivity in order to predict or achieve the best cell performance for a given one sun or concentrator cell design.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Intrinsic carrier concentration and minority-carrier mobility of silicon from 77 to 300 K

A considerable improvement in the accuracy of the measurement of the intrinsic carrier concentration in silicon near room temperature has recently been reported. This was achieved by the accurate analysis of minority-carrier current flow in specially fabricated p-n junction devices. In this paper this technique has been extended to measurements down to 77 K. A further improvement of the technique has been the simultaneous measurement of the minority-carrier electron mobility utilizing open-circuit voltage decay measurements.

Silicon surface damage caused by reactive ion etching in fluorocarbon gas mixtures containing hydrogen

For selective etching of SiO2 on silicon, gases or gas mixtures containing hydrogen are often used. Hydrogen from the glow discharge promotes the formation of a thin film polymer layer responsible for the selectivity of the etching process. The reactive ion etch (RIE) process is known to create damage in the silicon substrate. The influence of hydrogen on the damage and deactivation of dopants is investigated in the present work. The distribution of hydrogen in silicon, after different etching and annealing conditions have been studied. The influence of the RIE process on the charge carrier concentration in silicon has been investigated. Various analytical techniques like contact resistivity measurements, four point probe measurements, and Hall measurements have been used to determine the influence of the RIE process on the electrical properties of processed silicon wafers. The hydrogen profile in as-etched and post annealed wafers was determined by the 1H(15N,αγ)12C nuclear reaction. The depth of the deactivated surface layer is discussed in terms of the impinging hydrogen ion energy, i.e., the possibility of H+ ions to pick up an energy equal to the peak-to-peak voltage of the rf signal.

Electrical Properties of Platinum-Silicon Contact Annealed in an H2 Ambient

Annealed platinum-silicon contact electrical properties have been consistently investigated at the range of 6.0×1015∼8.5×1019 cm-3 silicon carrier concentration ND and in the 200∼700°C annealing temperature range. For diodes heat-treated at 300°C, having ND=6×1015 cm-3, nearly ideal Schottky barrier diodes are obtained. For ND≥7×1018 cm-3, ohmic contact is obtained. The situation is almost unchanged for up to the 500°C annealing temperature. However, by heat-treatment at above 600°C, the effective barrier height rapidly decreases and the carrier concentration range. Which yield ohmic contact characteristics, moves to lower values. These phenomena are satisfactorily interpreted on terms of “impurity pile up effect”. The impurities pile-up is revealed by the Auger electron spectroscopy analysis. Arsenic impurities are piled up at the platinum silicide-silicon interface. Presumably, piled up impurities near PtSi–Si interface are electrically activated at above the 600°C annealing temperture. Effectively, the interface carrier concentration is increased by about one order of magnitude in regard to the silicon substrate carrier concentration by 600°C annealing.

Anodic current measurements as a method to determine the carrier concentration in silicon

Anodic current measurements as a method to determine the carrier concentration in silicon

Anodic current measurements as a method to determine the carrier concentration in silicon

A method to determine the ionized-donor concentration in silicon based on anodic current measurements is presented. An original electrochemical set-up employing this method is also proposed and the results of the measurements in 0.1 M NaNO 3 and 1 M LiI are given.

Pseudo‐Brewster Angle Determination of Carrier Concentration

The Brewster angle has long been used to determine the index of refraction of nonabsorbing material. Semiconductors and other absorbing materials exhibit a nonzero minimum at a “pseudo‐Brewster” angle which depends on the wavelength of incident light and the optical constants of the materials. Since semiconductor infrared optical constants are strongly dependent on the carrier density, the pseudo‐Brewster angle is an indication of this density. An infrared, optical constant model for semiconductors has been used to calculate calibration curves relating carrier concentration in silicon to the pseudo‐Brewster angle for several wavelengths, the range of carrier concentrations being limited by the wavelength employed. Experimental results for silicon are presented for a wavelength of 3.391 µm.