Hole Drift Velocity Research Articles

High-field drift velocity of holes in inversion layers on silicon

We report measurements of the room-temperature drift velocity of holes along the (100) Si-SiO2 interface (drift direction [011]) as obtained by a time-of-flight technique. Our measured values range up to 60% higher than previously reported values at comparable tangential and normal electric fields. An empirical equation that fits the low-field mobility and the high-field velocity as a function of tangential and normal fields is presented.

Generalised small signal analysis of a DAR (Double Avalanche Region) Impatt diode

A generalised small signal analysis of a DAR Impatt diode has been carried out using recent values of ionisation rates and saturated drift velocities of electrons and holes for Si and GaAs taking both drift and diffusion of charge carriers into account. Results show similar discrete negative conductance frequency bands separated by positive conductance frequency bands for asymmetrical structure as in the ideal case[1] establishing that the harmonically related frequencies can be avoid in Si DAR Impatt diode. However, unlike the ideal case, here the symmetrical DAR Impatt also exhibits finite negative conductance. GaAs DAR Impatt shows similar variations of negative conductance as in Si at high frequencies (in the mm wave range) but at the low frequency side (< 1 GHz) it gives uniform negative conductance unlike Si where the negative conductance comes only at higher frequencies. In our calculations we have considered thin depletion layers (0.8, 1 μm and 2 μm) to show the usefulness of the device in the mm wave range. Further, the DAR Impatt will be able to withstand higher biasing current density without thermal runaway due to space charge cancellation and thus will deliver more power than the conventional Impatts.

Oscillation in Semiconductors with a Dumbbell-Shaped Structure

A new model of current oscillation observed in the current saturation regime of the current-voltage characteristic in semiconductors with a dumbbell-shaped structure is proposed. As the electron and hole drift velocities deviate from Ohm's law, an electric double layer is formed on the anode side of the narrow region of a sample and a negative resistance region appears on the cathode side. These formations in the sample cause the current oscillation. Experimental measurements of the potential distributions in the sample are carried out for n-type germanium and it is shown that these results can be explained well by the proposed model.

High-field transport of holes in silicon

The room-temperature drift velocity of holes in silicon has been measured for electric fields ranging from 9 to 234 kV/cm using a microwave time-of-flight technique. The measured velocity saturates at a value of 0.96±0.05×107 cm/sec at a field strength of 175 kV/cm.

Hole-drift velocity in natural diamond

The drift velocity of holes in natural diamond is analyzed for a wide range of temperatures $85\ensuremath{\le}T\ensuremath{\le}700$ K and fields ${10}^{2}lEl6\ifmmode\times\else\texttimes\fi{}{10}^{4}$ V/cm applied parallel to $〈100〉$ and $〈110〉$ crystallographic directions. Experiments are carried out with the time-of-flight technique, and theory uses a Monte Carlo method. The microscopic interpretation is based on a two-spherical and parabolic band model and considers lattice scattering only. Values ${m}_{h}=1.1{m}_{o}$ and ${m}_{l}=0.3{m}_{o}$ for heavy-and light-hole effective masses are found.

Flicker noise of hot holes in silicon at 78 K

From flicker-noise data versus applied voltage and current-voltage measurements on a p + πp + planar silicon device at 78 K we calculated Hooge's parameter α for flicker noise as a function of the electric field strength E 0 applied along the 〈1, 0, 0〉 crystallographic direction. We found that α( E 0) decreases with increasing field. For E 0 ⩽ 3 × 10 4 V/m the following relation holds: α( E 0) = α(0)/[1 + ( E 0/ E cℓ ) 2]. E cℓ is the field where the drift velocity of the light holes is within 10% of the sound velocity. This particular α( E 0) dependence indicates the connection between α( E 0) and the scattering of light holes by acoustic phonons.

Drift velocity of holes in germanium and silicon

The displaced Maxwellian distribution function as it applies to semiconductors with lattice limited scattering is discussed. It is shown that good agreement between theoretical results and experimental data for the drift velocity can be obtained if the phonon coupling constants are lowered somewhat from their correct values. Calculations are presented for p-type germanium and silicon and it is shown that the key factor that must be considered in both materials is the non-parabolicity of the valence bands.

On the lattice scattering and effective mass of holes in natural diamond

Drift mobility and high-field drift velocity of holes in natural diamond are investigated with the time-of-flight technique. A theoretical interpretation based on Monte Carlo simulation suggests possible values for the deformation potential parameters and effective masses.

Electrical properties and performances of natural diamond nuclear radiation detectors

Hole and electron drift velocities and mean free drift time have been measured with a time-of-flight technique as functions of electric field in crystals of natural diamond. The performances of diamond nuclear radiation detectors have been investigated using alpha and beta particles. An energy for electron-hole pair creation of 13.19 eV has been determined for alpha particles in the 5–6 MeV energy range. Spectral lines of alpha particles within this energy range have shown a resolution of 82 keV at room temperature.

Monte Carlo calculation of the drift velocity of electrons and holes in high electric fields in silicon mosfets

Monte Carlo calculation of the drift velocity of electrons and holes in high electric fields in silicon mosfets

A nonlinear circuit model for IMPATT diodes

An improved nonlinear circuit model for IMPATT diodes is presented for which each element bears a simple relationship with the physical operating mechanisms inside the device. The model contains lumped nonlinear elements as well as lumped and distributed linear elements. In its most general form it incorporates various second-order effects heretofore neglected in other circuit models. These include the effects due to unequal hole and electron ionization rates, unequal hole and electron drift velocities, and carrier diffusion.

Effect of impurity scattering on the hole drift velocity in germanium

The effect of the impurity-scattering mechanism on the hole drift velocity in Ge is studied for impurity concentration ${N}_{I}\ensuremath{\le}{10}^{17}$ ${\mathrm{cm}}^{\ensuremath{-}3}$ at 77 and 300 K. Results, which account for warping and nonparabolic effects of the heavy-hole band, complete an analysis previously published.

Charge carrier drift mobility in polycrystalline tetracene layers

The charge carrier drift mobility in tetracene layers was measured using the time-of-flight method. Free carriers were generated by short electron pulses. At electric fields E > 2 × 10 4V cm −1 the drift velocity of holes is constant, i.e. the drift mobility is proportional to the reciprocal electric field: μ h ∝ E −1.

Enhancement of hole drift velocity in amorphous As 2Se 3 by iodine doping

The addition of ∼ 0.6 at.% iodine to approximately stoichiometric a-As 2Se 3 enhances the hole drift velocity by more than a decade but does not affect its field, thickness and temperature dependence or the degree of disorder. It is speculated that iodine reduces the ratio of trapping to hopping states in the trap-controlled hopping process which recently has been proposed for a-As 2Se 3.

Correction to "Electron and hole drift velocity measurements in silicon and their empirical relation to electric field and temperatures"

Correction to "Electron and hole drift velocity measurements in silicon and their empirical relation to electric field and temperatures"

Dispersive Low-Temperature Transport ina-Selenium

Transient hole transport in $a$-Se below 180 K is shown to be a stochastic process. The transition from the well-defined high-temperature transport with Gaussian dispersion to the low-temperature stochastic transport is not paralleled by a change in the activation energy of the hole drift velocity.

Charge transport in layer semiconductors

Electron and hole-drift velocity is measured in the layer semiconductors HgI 2, GaSe, PbI 2 and GaS, mainly on the direction parallel to the c-axis between 80 and 400 K. In the electric field range in question, electron and hole-drift velocity is proportional to the field except in the case of GaS, where a superohmic behaviour is observed. At 300 K the mobility parallel to the c-axis is μ e, = 100 cm 2 Vsec , μ h = 4 cm 2 Vsec for HgI 2; μ e = 80 cm 2 Vsec , μ h = 210 cm 2 Vsec for GaSe; μ e, = 8 cm 2 Vsec , μ h = 2 cm 2 Vsec for PbI 2. The highest hole mobility observed in GaS is μ h = 80 cm 2 Vsec . Where it is possible to compare these data with mobility values perpendicular to the c-axis, the three-dimensional character of the energy bands near the fundamental gap is proved. For HgI 2 and GaSe we find no evidence for the large anisotropy of charge-carrier transport properties usually attributed to layered semiconductors. The mobility-temperature dependences found are interpreted on the basis of polar and non-polar optical phonon scattering mechanisms, except in the case of GaS, where a trapping model is used. The effective masses of electrons and holes are reported for PbI 2 and, for the first time, for HgI 2.

Electron and hole drift velocity measurements in silicon and their empirical relation to electric field and temperature

The drift velocity of electrons and holes in silicon has been measured in a large range of the electric fields (from 3 . 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> to 6 . 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> V/cm) at temperatures up to 430 K. The experimental data have been fitted with a simple formula for the temperatures of interest. The mean square deviation was in all cases less than 3.8 percent. A more general formula has also been derived which allows to obtain by extrapolation drift velocity data at any temperature and electric field.

On the time dependency of the avalanche process in semiconductors

An equation is derived for the time dependent current in the avalanche region of a uniform diode, for the case of one charged carrier of either electron or hole is injected, for unequal ionization rates and drift velocities of electrons and holes. The appearing time-constant differs from earlier results, derived on the basis of the well known intrinsic response time. The noise characteristics of the current are established for a Poissonian injection of an electron or hole. The factor which describes the influence of the statistics of the multiplication for low frequencies, is also found to differ from previous published results. At high current multiplication factors the present study is in agreement with previous work.

Measurement of the drift velocity of charge carriers in mercuric iodide

The time-of-flight technique has been used to determine the electron and hole drift velocities in mercuric iodide crystals. The electron mobility is constant up to fields of 30 kV/cm, equal to 100 cm2/V sec at room temperature, and proportional to T−0.9 in the temperature range 114–300 °K. The hole mobility is equal to 4 cm2/V sec at room temperature and exhibits a T−1.7 dependence between 140 and 240 °K and a T−3.7 dependence between 240 and 350 °K.