Tunneling through the space charge region in a metal-amorphous silicon contact

By solving for the potential barrier profile in metal-amorphous silicon contacts using an exponential distribution of the density of states in the energy spectrum mobility gap, we compute the voltage-current characteristics of such contacts taking into account tunneling through the space charge region. We demonstrate that as the density of states in the middle of the mobility gap increases, such tunneling leads to significant changes in the rectifying properties of a metal-amorphous silicon contact.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 3–7, November, 1986.     

Effect of an electric field in the space charge region on surface states

The quantization of the current carriers and the effect of an electric field in the space charge region on Tamm surface states are investigated within the framework of the Kronig-Penney model and in the effective mass approximation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 70–77, October, 1991.     

Electron-phonon coupling in highly doped n type silicon

The effect of free electrons on the optical phonon of silicon at the center of the Brillouin zone is studied using the Raman scattering technique. Heavy doping gives rise to a continuous electronic Raman scattering and makes the phonon line shape assymetric. The profile factor which is related to the disymetry, is shown to have the signes of the matrix elements of the electron-phonon interaction.     

Effect of surface defects on radiative interband recombination in silicon nanocrystals highly doped with hydrogen-like impurities

The role of surface defects at the Si nanocrystal boundary during the process of interband radiative recombination is studied in the case in which nanocrystals are doped with hydrogen-like impurities with shallow energy levels. It is shown that, in the case of a nonpassivated surface with a large number of dangling bonds, the rate of radiative transitions in nanocrystals doped with donors can be larger than that in nondoped crystallites. On the other hand, doping with acceptors leads to a decrease in the rate of transitions. In the case of a completely passivated surface, the recombination rate remains almost unchanged irrespective of the type of dope.     

Spectroscopy of surface space charge layers

Spectroscopic studies of the semiconductor surface space charge layer system complement and enlarge on the information derived from dc transport experiments. The paper fkst gives an account of far-infrared cyclotron resonance and dynamical conductivity studies in the surface layer. Such work explores the carrier motion in the plane of the space charge layer. A later section discusses intersubband spectroscopy, experiments in which the quantized motion in bound levels normal to the surface is probed.     

Strong correlations enhanced by charge ordering in highly doped cobaltates

We present an explanation for the puzzling spectral and transport properties of layered cobaltates close to the band-insulator limit, which relies on the key effect of charge ordering. Blocking a significant fraction of the lattice sites deeply modifies the electronic structure in a way that is shown to be quantitatively consistent with photoemission experiments. It also makes the system highly sensitive to interactions (especially to intersite ones), hence accounting for the strong correlations effects observed in this regime, such as the high effective mass and quasiparticle scattering rate. These conclusions are supported by a theoretical study of an extended Hubbard model with a realistic band structure on an effective kagome lattice.     

Two-dimensional plasmons in hole space charge layers on silicon

We have observed two-dimensional plasmons in hole space charge layers of silicon. On Si(110) surfaces the plasmon mass depends on the charge density and shows a significant anisotropy for different directions of the plasmon wavevector in the surface. The determination of the plasmon mass allows detailed informations on the anisotropic and nonparabolic 2-D bandstructure of hole space charge layers.     

Hydrogen adsorption and surface structures of silicon

The adsorption of atomic hydrogen on silicon (111)2 × 1 cleaved, (111) 7 × 7, and (100) 2 × 1 surfaces has been studied by using electron energy loss spectrscopy (ELS) and Photoemission spectroscopy (UPS). On all surfaces the hydrogen removes the “dangling bond” surface state and a new peak in the density of states at lower energies corresponding to the SiH bond is found. The LEED pattern of the equilibrium surfaces (111) 7 × 7 and (100) 2 × 1 is not altered by hydrogen adsorption, while on the cleaved (111) 2 × 1 surface the fractional order spots are extinguished. The Haneman surface-buckling model therefore provides an explanation for the surface reconstruction of the cleaved (111) 2 × 1 surfaces. For the equilibrium surfaces, (111) 7 × 7 and the (100) 2 × 1, the data are consistent with the Lander-Phillips model.     

Annealing characteristics of highly doped ion implanted phosphorus layers in silicon

A combination of sheet resistance, stripping and Hall effect measurements have been made on phosphorus layers implanted into silicon at 40 and 100 keV with doses between 1 × 10¹⁵ and 5 × 10¹⁶ atoms/cm². The implants were made at room temperature and 450°C. After annealing at 650°C, the profile of electrically active phosphorus following a high dose room temperature implant, was found to be flat topped with a concentration of approximately 5 × 10²⁰/cm³. Very little diffusion occurred when annealing to 850°C where the free electron concentration increased to approximately 1.5 × 10²¹/cm³. Highly doped channeled tails were found when implanting at 450°C along the 〈110〉 direction and damage was being continuously annealed out preventing the formation of an amorphous phase. The rapid diffusion of the profile into the bulk found when annealing between 650°C and 850°C was speculated to be due to the presence of a dense dislocation entanglement in these layers following a hot implant.     

Hydrogen pile-up at interfaces between differently doped layers of amorphous silicon

Hydrogen profiles for layered a-Si:H structures are presented. Substantial accumulation of hydrogen at the p-i interface is found. Additional incorporation of hydrogen in p-layers is also observed for intermediate boron doping levels compared to intrinsic layers. Hydrogen profiles in single pin and in pinpin amorphous silicon structures enable determination of individual layer thickness.     

Magnetoreflectance of surface space charge layers on PbTe

We report the observation of cyclotron resonance of bound carriers in inversion and accumulation layers on p-PbTe. The resonance appears as an electric-field induced change in the magnetoreflectivity and is accompanied by changes in the volume cyclotron resonance structure.     

X-ray diffraction study of silicon single crystals highly doped with boron

The section Lang method of X-ray diffraction topography in combination with X-ray diffractometry based on the Borrmann effect was previously shown to be effective for detection of cluster formation during the growth process of highly doped Si-Cz single crystals. In the present work, the same techniques have been used to choose the best condition of technological heat treatment of boron-doped silicon from the view-point of formation of microdefects. The concentration and average size of dislocation loops have been calculated for two conditions of standard heat treatment from the analysis of diffusion scattering. The distribution of dislocation loops along the growth axis and crystal diameter has been determined as well.     

Radiative recombination associated with a two-dimensional space charge layer in silicon

We present photoluminescence measurements in Si-MOS structures in presence of a two-dimensional space charge layer. A unique feature is observed: the electron-hole droplet and exciton recombinations are quenched, and a new radiative recombination channel appears, in presence of an electron space charge layer at the (1 1 1) and the (1 1 0) surfaces and of a hole space charge layer in the (1 0 0) surface. The dependence of the energy of this new band on the two-dimensional carrier concentrations is given and a simple model to explain the observed features is proposed.     

A prototype silicon detector system for space cosmic-ray charge measurement

A readout electronics system used for space cosmic-ray charge measurement for multi-channel silicon detectors is introduced in this paper, including performance measurements. A 64-channel charge sensitive ASIC (VA140) from the IDEAS company is used. With its features of low power consumption, low noise, large dynamic range, and high integration, it can be used in future particle detecting experiments based on silicon detectors.     

A prototype silicon detector system for space cosmic-ray charge measurement

A readout electronics system used for space cosmic-ray charge measurement for multi-channel silicon detectors is introduced in this paper, including performance measurements. A 64-channel charge sensitive ASIC （VA140） from the IDEAS company is used. With its features of low power consumption, low noise, large dynamic range, and high integration, it can be used in future particle detecting experiments based on silicon detectors.     

Strong dopant dependence of implantation defect accumulation and amorphisation in highly doped silicon

A very strong influence of the dopant material in highly doped silicon on the defect accumulation rate has been found. A boron concentration of 2 at% shifts the amorphisation dose for 80 keV Ne⁺ ions by a factor of more than 10 to about 3 × 10¹⁶ cm^-2 at a RT implantation.     

Ionization transients of shallow levels in silicon space charge layer at low temperature

In silicon diodes, at cryogenic temperatures, transient currents due to the depletion layer formation are not monotonic in time, but present a peak. It is shown that, taking appropriate experimental cares, these transient currents are accurately described by a theoretical model based on Frenkel-Poole effect. Particularly, the influence of compensation, through its bulk resistivity effect, is discussed. Both n and p-type silicon diodes are shown to exhibit the same features, contrary to some author's assertion.     

Space charge and surface state characteristics of the silicon/electrolyte interface

The essentially blocking nature of the silicon/electrolyte (S/E) interface enables charge to be induced electrostatically at the interface by an applied bias. The use of pulsed rather than DC biases provides a fairly detailed picture of the silicon interface. The results reported here concern the silicon space-charge layer, localized states at the S/E interface and charge leakage across the interface. As to the first, evidence is presented that strong, quantized accumulation layers of excess surface-electron densities as high as 10¹⁴ cm⁻² can be induced at the Si surface, an order of magnitude larger that can be attained in Si inversion layers in MOS structures. The localized states are of total density of about 10¹² cm⁻² and of capture cross sections around 5 × 10⁻¹⁸ cm². The nature of these states is not known; they are probably fast surface states at the silicon surface. The charge leakage occurs under strong accumulation conditions, very likely by electron tunneling from the silicon electrode into the electrolyte. It takes place practically instantaneously, but the leaked charge remains stored near the interface for a considerable time. Some suggestions concerning this unexpected behavior are put forward.     

表层氟化温度对聚乙烯中空间电荷积累的影响

在实验室反应釜中于不同的温度(35 ℃, 55 ℃和70 ℃) 下, 以氟气体积浓度为12.5%的氟/氮混合气对热压制备的聚乙烯(PE) 片状试样(厚约0.8 mm) 进行了相同时间(2 h) 的表层氟化改性. 利用压力波法研究了氟化温度对PE中空间电荷积累的影响. 结果显示, 随着氟化温度的提高直流高压作用下的氟化试样中的空间电荷积累明显减少, 这个70 ℃的氟化试样中几乎没有空间电荷. 衰减全反射红外分析表明, 氟化引起了试样表层化学组成的本质变化及氟化度随氟化温度的明显提高. 接触角测量与表面能计算间接地表明了这些氟化层有显著增大的介电常数. 开路热刺激放电电流测量进一步揭示了这些氟化层 不同的电荷捕获特性, 及随着氟化温度的提高氟化层对化学杂质从半导性电极向PE扩散的增强的阻挡特性, 因此表明氟化层中自由体积的相应减小. 表层自由体积的减小对抑制空间电荷的积累, 比介电常数的增大和电荷陷阱的变化起到更加显著的作用.     

A model for surface space charge in thin films of AgBr

A model for the surface space charge layer in ionic crystals has been developed for thin films where the film thickness is less than or comparable to the Debye length. A potential difference between the surface and the bulk is present which depends on the film thickness and the impurity concentration. The implications of this model have been examined with respect to thin films of AgBr at room temperature.