Calculation of the trapping of hot electrons by repulsive centers under the conditions of a needle-type distribution function

The trapping coefficient of hot electrons repelled by a Coulomb center is calculated explicitly for a needle-shaped electron distribution function under conditions where the effective trapping cross section, along with the Sommerfeld factor, depends exponentially on the energy of the electron which has tunneled through the barrier. The criteria under which the effective Bonch-Bruevich cross section is valid are obtained. Fiz. Tekh. Poluprovodn. 31, 944–946 (August 1997)     

Energy relaxation of photoexcited hot electrons at very low temperatures

The scattering of electrons with energy $\text{?<}\text{1}\text{2}\text{ms}{}^2$ by acoustical phonons at very low temperatures T?ms² is investigated.     

Thermal capture of electrons and holes at zinc centers in silicon

The thermal capture rates of electrons and holes at zinc centers in silicon are obtained in reversed biased N⁺P and P⁺N diodes from junction capacitance transients due to capture of photogenerated and injected carriers. The electric field dependence of the thermal capture rates of holes at singly ionized zinc centers is E^?1·1, while that at doubly ionized zinc centers is exp(?E/E₀). The temperature dependence of the thermal capture rate of holes at doubly ionized zinc centers is small. The thermal capture rate of electrons at neutral zinc centers is 2·0×10^?9cm³/sec with very little field dependences, while that at singly ionized zinc centers is 5·0×10^?11cm³/sec with very little field and temperature dependence below 170°K. Auger-impact emission rate of electrons trapped at doubly ionized zinc centers by electrons is 3·5×10^?10cm³/sec with very little field and temperature dependence below 170°K.     

Equivalent temperature of hot electrons

The two extensions of the Einstein relation qD_par = kT_eμ_par and qD_par = kT′_eμ′_and define, in the case of hot electrons, two different electron temperatures T_e and T′_e. It is shown here that the two interpretations are fully equivalent in that they lead to the noise expressions $\text{S}{}_{\mathrm{I}}\text{(0)=4kT(}\text{I}\text{V}\text{and}\text{S}{}_{\mathrm{I}}\text{(0) = 4kT′}{}_{\mathrm{e}}\text{(}\text{d}\text{I}\text{d}\text{V}\text{)}$, respectively. The T′_e interpretation, however, is slightly favored, since it leads to the simple expression $\text{S}{}_{\mathrm{V}}\text{(0) = 4kT′}{}_{\mathrm{e}}\text{/}\text{d}\text{I}\text{d}\text{V}\text{)}$ for the open-circuit noise.     

Thermal emission rates and activation energies of electrons at tantalum centers in silicon

The thermal emission rates and activation energies of electrons trapped at the two Ta donor centers in n-type silicon are determined from transient capacitance measurements on Schottky barrier diodes made on phosphorus and tantalum doubly doped silicon crystals. The thermal activation energies are 232 and 472 meV for the two donor levels below the conduction band edge and the pre-exponential factors, A, are both 1.5 × 10¹⁰ sec^?1 in the Ahrrenius equation for the emission rate, $\text{A (}\text{T}\text{300)}{}^2\text{exp}\text{(}\text{> ?ΔE}\text{k}{}_{\mathrm{B}}\text{T}\text{)}$.     

Silicon surface emission of hot electrons

A new emission model, based on a probabilistic treatment of electron trajectories, is developed for hot electron emission from a silicon surface. Primary electrons, generated thermally or optically, are heated by a normal electric field and cooled by phonon collisions and by impact ionization. Unlike the case in previous models, the semiconductor field need not be uniform, and multistage phonon processes are included. The model provides hot electron energy distributions both for electrons transported in the non-equilibrium layer at the silicon surface and for electrons emitted into the oxide. It shows that the most probable trajectory of an emitted electron is not one of zero collisions (as assumed in the analysis of Verwey et al. [2]), but one involving the generation of many optical phonons. The model, used together with photoexcited hot electron measurements (as developed by Ning and Yu [6]), also provides an accurate method for determining phonon and ionization mean free paths.     

Negative dielectric relaxation of hot electrons in CdTe

A direct measurement of negative dielectric relaxation in CdTe at room temperature is presented at electric fields where electrons exhibit negative differential mobility. Data have been obtained with the time-of-flight technique, which is suitable to investigate electron diffusion process and space charge effects by means of an analysis of the time and space evolution of an electron charge layer drifting in a semiconductor material exhibiting either positive or negative differential mobility.     

Transmission of hot electrons through a metal-semiconductor interface

The expression for the current density of the chemical electron emission from a metal film into a semiconductor is obtained. The dependences of the probability for transmission of hot electrons through the metal-semiconductor interface on the average hot-electron energy, temperature, and electric-field strength are obtained. The conditions at which the probability for transmission of hot electrons through the interface is almost equal to unity are established.     

Numerical modeling of hot electrons in n-GaAs Schottky-barrierdiodes

The drift-diffusion model, with the inclusion of the energy balance equations, is used to model DC properties of n-GaAs Schottky diodes at high forward bias voltages. The boundary condition for the energy balance equation at the Schottky contact is based on the assumption that the energy flow across the interface is equal to the energy carried by the electrons. The effects of thermionic-field emission and image force lowering are modeled with a field-dependent barrier height. The incorporation of these two effects resulted in very good agreement between simulated and measured I-V characteristics for diodes with different doping concentrations of the epitaxial layer     

Diffusion of hot electrons in n indium phosphide

The diffusion-conefficient/field characteristic has been calculated for n indium phosphide. The resulting curves show several pearks and minima. The origin of these features is discussed.     

Comparison of thermal runaway limits under different test conditions based on a 4.5 kV IGBT

This investigation focuses on determining the temperature-dependent leakage current limits which compromise the blocking safe operating area for silicon IGBT technologies. A discussion of a proper characterization method for selecting the maximum rated junction temperature for devices operating at high temperatures is given by comparing the different testing methods: Static performance (including and excluding self-heating effects), Short Circuit Safe Operating area and High-Temperature Reverse Bias. Additionally, a thermal model is used to predict the junction temperature at which thermal runaway takes place. In this paper guidelines are proposed based on the correlation among short circuit withstand capability and off-state leakage current for guarantying reliable operation and ensuring that they are thermally stable under parameter variations. This study is helpful to facilitate application engineers for defining the correct stability criteria and/or margins in respect of thermal runaway.     

The distribution function of hot charge carriers under conditions of resonance scattering

A simple analytical method for solving the kinetic equation for charge carriers in the presence of resonance states in the streaming mode is suggested. The Breit-Wigner isotropic model for resonance scattering was used in an analysis of both the anisotropic energy distribution of charge carriers, which arises under the effect of an external electric field in a two-and three-dimensional gas of charge carriers, and the occupancy of the resonance state. The conditions for the origination of the intracenter population inversion are considered.     

Spin filtration of unpolarized electrons by impurity centers in semiconductors

It is shown that unpolarized paramagnetic centers can implement the spin filtration of unpolarized conduction electrons in semiconductors. This ability of paramagnetic centers is caused by the difference in the spin evolution of the states of electron-paramagnetic-center pairs and by the spin selectivity of electron capture exclusively from singlet pairs. The electron spin polarization should be opposite to the paramagneticcenter polarization. To implement spin filtration, an external magnetic field is necessary. The polarization can attain the largest values (∼10%) if the probability of spin-selective electron capture from singlet pairs exceeds the pair-decay rate by a factor of 5–7.     

Metal-to-semiconductor emission of hot electrons excited on catalytic reaction

The properties necessary for the chemoemission of hot electrons through the interface between a metal film and a semiconductor are established for a metal-semiconductor structure in which hot electrons are excited during a catalytic reaction at the interface between the metal film and the gas mixture. The possibility of generating electric energy using a method based on this effect is substantiated.     

Transport of electrons in monolithic hot electron Si transistors

The transport of electrons across the base of monolithic hot electron transistors is studied using a simplified model. The base is assumed to be limited by abrupt barriers and no account is taken of backscattering from the collector region. The collisions in the base are considered to be of only one type which represents an average between interactions with optical and acoustic phonons. A fundamental part in the analysis is played by the function P_EX(i, x), (i = 1, 2, …) which gives the total probability of exit into the collector of an electron whose ith collision occurs at a point of abscissa x within the base. The function P_EX(i, x) is determined iteratively for decreasing values of i, using the theorem of compound probabilities, and from there the transport factor across the base is derived. Programs have been written to this effect, and the results are illustrated by means of examples which demonstrate the effect on the transport factor of the various parameters of the device, and show some comparisons with a previous theory[4].     

Emission probability of hot electrons for highly doped silicon-on-sapphire IGFET

Experimental measurements of the probability of emission of hot electrons into the oxide of silicon-on-sapphire (SOS) MOS devices are presented for high doping levels. The experimental method is derived from the optically induced hot electron experiment as proposed by Ning. The dependence of the emission probability on device parameters and applied voltage is analyzed emphasizing the lucky electron model and the sensitivity of the model to device characterization. We found that the expressionP = P'_{0} exp (-d/lambda_{eff})describes the experimental data very well, takingP'_{0} = 0.5andlambda_{eff} = 95Å. It shows that hot carrier properties of SOS are the same as those of bulk silicon. The results also show that hot electron related instabilities can arise for bias voltages lower than 2 V when the doping level reaches 1 × 10¹⁸At/cm³.     

Mean energy of photoexcited hot electrons in high magnetic fields

Several authors have determined the mean energy of a photoexcited electron gas in the absence of magnetic field. Assuming a Maxwellian distribution for the electrons, they used the power balance equation to find the electron temperature T_e. Noting that when a strong magnetic field is applied, the electron collision integral vanishes in the extreme quantum limit, we derive a theoretical expression for T_e using a similar approach. Recombination and various scattering processes by optical and acoustical phonons are considered and the dependence of T_e on magnetic field, lattice temperature and laser excitation freqeuency is studied.     

Vertical transport of hot electrons in GaAs/AlAs superlattices

Ballistic transport of hot photoexcited electrons injected from a superlattice into an enlarged quantum well is studied using the polarized hot photoluminescence technique. It is established that most photoexcited electrons thermalize before they are captured by the enlarged QW; however, a minor fraction of them reach the enlarged quantum well ballistically, keeping their momentum-distribution anisotropy or spin orientation arising due to the absorption of linearly or circularly polarized light in the superlattice.     

Investigation of the shift of hot spot in lateral diffused LDMOS under ESD conditions

This paper investigates the thermal behavior and thermal distribution of the high voltage LDMOS under Electrostatic Discharge (ESD) stress. It shows that the hot spots shift in both two-dimension and three-dimension during the snapback behavior and these spots are potential failure positions for the inferior structures. According to the different breakdown position, two improved adaptive structures which are verified by the simulations and experiment results are proposed. The article makes contribute to design more robust ESD protection power devices. The high voltage LDMOS is demonstrated in 0.5 μm CDMOS technology.