Carrier mobilities in silicon empirically related to doping and field

Caughey, D.M.; Thomas, R.E.

doi:10.1109/proc.1967.6123

Cited by 1,474 publications

(514 citation statements)

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“…As implantation dose is fixed, sheet resistance should not vary as a function of temperature once all boron atoms have been activated, given the limited variation of mobilities in the doping range of 10 18 cm À3 to 10 20 cm À3 considered here. 40 On the contrary, the boron source is virtually infinite in the case of diffused emitters, and consequently, the boron concentration in silicon is in this case determined by temperature. Figure 1(a) shows that, in implanted emitters, sheet resistance saturates at temperatures of 950 C and beyond, reaching a value of approximately 170 X/sq in bSi.…”

Section: Experimental Results On Diffused and Implanted Emittersmentioning

confidence: 99%

Recombination processes in passivated boron-implanted black silicon emitters

Gastrow

Ortega

Alcubilla

et al. 2017

Journal of Applied Physics

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Recombination processes in passivated boron-implanted black silicon emitters In this paper, we study the recombination mechanisms in ion-implanted black silicon (bSi) emitters and discuss their advantages over diffused emitters. In the case of diffusion, the large bSi surface area increases emitter doping and consequently Auger recombination compared to a planar surface. The total doping dose is on the contrary independent of the surface area in implanted emitters, and as a result, we show that ion implantation allows control of emitter doping without compromise in the surface aspect ratio. The possibility to control surface doping via implantation anneal becomes highly advantageous in bSi emitters, where surface passivation becomes critical due to the increased surface area. We extract fundamental surface recombination velocities S n through numerical simulations and obtain the lowest values at the highest anneal temperatures. With these conditions, an excellent emitter saturation current (J 0e ) is obtained in implanted bSi emitters, reaching 20 fA/cm 2 6 5 fA/cm 2 at a sheet resistance of 170 X/sq. Finally, we identify the different regimes of recombination in planar and bSi emitters as a function of implantation anneal temperature. Based on experimental data and numerical simulations, we show that surface recombination can be reduced to a negligible contribution in implanted bSi emitters, which explains the low J 0e obtained. Published by AIP Publishing. [http://dx

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Section: Experimental Results On Diffused and Implanted Emittersmentioning

confidence: 99%

Recombination processes in passivated boron-implanted black silicon emitters

Gastrow

Ortega

Alcubilla

et al. 2017

Journal of Applied Physics

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“…6. Caughey and Thomas [18] found that the drift velocities can be well described by the empirical formula:…”

Section: Figurementioning

confidence: 99%

Severe signal loss in diamond beam loss monitors in high particle rate environments by charge trapping in radiation‐induced defects

Kassel¹,

Guthoff

Dabrowski

2016

Physica Status Solidi (a)

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The Beam Condition Monitoring Leakage (BCML) system is a beam monitoring device in the CMS experiment at the LHC. As detectors 32 poly-crystalline (pCVD) diamond sensors are positioned in rings around the beam pipe. Here high particle rates occur from the colliding beams scattering particles outside the beam pipe. These particles cause defects, which act as traps for the ionization, thus reducing the charge collection efficiency (CCE). However, the loss in CCE was much more severe than expected from low rate laboratory measurements and simulations, especially in single-crystalline (sCVD) diamonds, which have a low initial concentration of defects. After an integrated luminosity of a few fb −1 corresponding to a few weeks of LHC operation, the CCE of the sCVD diamonds dropped by a factor of five or more and quickly approached the poor CCE of pCVD diamonds. The reason why in real experiments the CCE is much worse than in laboratory experiments is related to the ionization rate.At high particle rates the trapping rate of the ionization is so high compared with the detrapping rate, that space charge builds up. This space charge reduces locally the internal electric field, which in turn increases the trapping rate and recombination and hence reduces the CCE in a strongly non-linear way. A diamond irradiation campaign was started to investigate the rate dependent electrical field deformation with respect to the radiation damage. Besides the electrical field measurements via the Transient Current Technique (TCT), the CCE was measured. The experimental results were used to create an effective deep trap model that takes the radiation damage into account. Using this trap model the rate dependent electrical field deformation and the CCE were simulated with the software SILVACO TCAD. The simulation, tuned to rate dependent measurements from a strong radioactive source, was able to predict the nonlinear decrease of the CCE in the harsh environment of the LHC, where the particle rate was a factor 30 higher.

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“…Thus, the contradictory behavior with respect to the relative proportion of lattice or impurity scattering cannot be explained by unknown impurity effects. The dependence of the mobility on carrier density for the three theoretical fits to the data are all fit by the empirical Caughey-Thomas curve [19] with different parameters. At the lower carrier densities the C-D and Drude mobilities are much higher than previous measurements [3,19].…”

mentioning

confidence: 99%

“…The dependence of the mobility on carrier density for the three theoretical fits to the data are all fit by the empirical Caughey-Thomas curve [19] with different parameters. At the lower carrier densities the C-D and Drude mobilities are much higher than previous measurements [3,19]. At carrier densities above 10 17 cm 23 these differences disappear and the theories converge.…”

mentioning

confidence: 99%

Nature of Conduction in Doped Silicon

1997

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Via ultrafast optoelectronic THz techniques, we are able to test alternative theories of conduction by precisely measuring the complex conductivity of doped silicon from low frequencies to frequencies higher than the plasma frequency and the carrier damping rate. These results, obtained for both n and p-type samples, spanning a range of more than 2 orders of magnitude in the carrier density, do not fit any standard theory. We only find agreement over the full frequency range with the complex conductivity given by a Cole-Davidson type distribution applied here for the first time to a crystalline semiconductor, and thereby demonstrate that fractal conductivity is not just found in disordered material.[ S0031-9007(96) The frequency dependent complex conductivity is one of the most basic properties describing doped semiconductors. Associated with the conductivity are the key parameters characterizing the dynamics of the free carriers in semiconductors, the plasma frequency v p , and the carrier damping rate G 1͞t, where t is the carrier collision time. Characteristically, v p and G have THz frequencies. Even though the complex conductivity has been a topic of theoretical studies for several decades, complete experimental characterizations from low frequencies to beyond several THz have only started to be performed [1,2].Here we report definitive measurements of the complex conductivity from dc to 2.5 THz on doped silicon. Compared to earlier experimental studies of doped silicon [1,3], these new results have sufficient frequency range and precision to test alternative theories [4][5][6][7][8][9][10][11][12] for the conductivity. However, for both n-and p-type silicon and over a measured range of more than 2 orders of magnitude of the carrier density we do not find agreement with any standard theory, including Drude, lattice-scattering, and impurity-scattering theories. As a result, we were forced to look outside the standard theoretical approaches.Our interest in a Cole-Davidson type distribution was motivated by the close relationship between the Debye theory of dielectric insulators and Drude theory, the simplest theory of electrical conduction. For Debye theory, in response to a step-function electric field, the polarization is established exponentially with a characteristic response time. Similarly, for Drude theory, in response to a stepfunction E field, the current is established exponentially with the carrier collision time. Consequently, in the frequency domain the mathematical representations of these two theories are identical. It has been found experimentally that for relatively low frequencies the complex dielectric constants of disordered materials, such as molecular liquids [13], polymers [14], and more recently ionic glasses [15,16], show better agreement with a modified Debye spectral response, known as the Cole-Davidson (C-D) distribution. In the frequency domain, the C-D distribution corresponds to Debye theory with a fractional exponent b, limited to values between 0 and 1, and reduces to Debye th...

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Carrier mobilities in silicon empirically related to doping and field

Cited by 1,474 publications

References 8 publications

Recombination processes in passivated boron-implanted black silicon emitters

Recombination processes in passivated boron-implanted black silicon emitters

Severe signal loss in diamond beam loss monitors in high particle rate environments by charge trapping in radiation‐induced defects

Nature of Conduction in Doped Silicon

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