Maximum free charge in two-phase surface charge-coupled devices

Maximum free charge in two-phase surface charge-coupled devices

World Abstracts on Microelectronics and Reliability rigorous treatment of the transverse magnetic field waves and carrier waves is given without use o...

130KB Sizes 1 Downloads 35 Views

World Abstracts on Microelectronics and Reliability rigorous treatment of the transverse magnetic field waves and carrier waves is given without use of the so-called quasi-static approximation. The assumption of zero diffusion is not used. The field waves are characteristic of EM waves in a lossy medium; the carrier waves consist of two types: the solenoidal and non-solenoidal waves. It is found that the solenoidal wave may include leaky modes. Equivalent surface admittance and a dielectric constant are obtained on using Barybin's free boundary conditions.

The fT of bipolar transistors with thin lightly doped bases. J. R. A. BEAL and J. A. G. SLATTER. Solid-State Electron. 19, 549 (1976). The f r of bipolar transistor is normally increased by decreasing the base doping density and width. At very small widths and densities this improvement may not occur because injection modulation of the base charge at normal operating currents then increases emitter junction resistance, re, and so makes the emitter time constant, re. Cre, larger. Simple expressions are given for re and f r in this situation and the theory is compared with measurements on sets of transistors in which f r is found to be largely independent of impurity charge in the base.

Critical concentration for metallization of doped germanium and silicon. K. F. BERGGREN and B. SERNELIUS. Solid-State Commun. 19, 487 (1976). An elementary model for the metal--non metal transition in n-type Ge and Si is considered. The model is based on recent theoretical work on electron-hole droplets in illuminated semiconductors. The energy of the metallic phase is computed from experimentally known values of the conduction band effective masses and the background dielectric constant. The critical concentration is determined approximately by comparing the energy of the metallic phase with the energy of an isolated donor atom (a bound electron-impurity ion pair). The theoretical estimates of the critical concentration agree in order of magnitude with experiments. The trend in chemical shifts is reproduced. Polarizability of shallow donors in silicon--a reply. T. G. CASTNER and N. K. LEE. Solid-State Commun. 19, 323 (1976). A reply to the comment of Yoshihiro and Yamanouchi is made explaining the role of Schottky barriers on the capacitance results determined previously by Bethin, Castner, and Lee. Earlier concentration-dependent di-electric constant measurements for Sb-doped Ge are also noted.

A study of the gold acceptor in a silicon p + n junction and an n-type MOS capacitor by thermally stimulated current and capacitance measurements. MARTIN G. BUEHLER and WILLIE E. PHILLIPS. Solid-State Electron. 19, 777 (1976). The thermally stimulated current and capacitance responses of a gold doped p + n junction and n-type MOS capacitor were measured experimentally and modeled theoretically for the case of majority-carrier defect charging. The gold acceptor atoms are initially charged with electrons at low temperatures, and during the heating cycle, excess electrons are released from the gold atoms. The thermally stimulated currentresponse for this phase is similar in both structures and has a distinctive peak-andvalley shape and an emission temperature about 220 K. During the steady-state phase, a current peak occurs in the MOS capacitance response. A physical model was developed and the influence of various parameters on the current and capacitance measurements was quantified. Various analytical schemes are described which allow rapid identification of the gold defect center and rapid computation of its density. A simple and inexpensive apparatus is described which is capable of heating rates as high as 10 K/s.

529

Comments on the hole mass in silicon inversion layers. G. LANDWEHR, E. BANGERT, K. VON KLITZING and TH. ENGLEST. Solid-State Commun. 19, 1031 (1976). Published experimental data for hole masses mc in silicon inversion layers on (110), (111) and (100) surfaces are critically discussed. New results are presented for the (100) orientation. It is shown that self-consistent calculations of m~ agree with those experimental data, which are compatible with cyclotron resonance results. It is demonstrated that a theoretical treatment by Falicov and Garcia, which predicts too large hole masses, is not tenable. Theory of iron-group impurities in II-VI compounds. S. W. BIERNACKI. J. phys. Chem. Solids 37, 819 (1976). A new method is developed for the description of the electronic 3d levels of the paramagnetic impurities in II-VI compounds. The method is based upon the linear-combinationof-atomic-orbitals approximation. The effective one-electron Hamiltonian, taken as a sum of the kinetic energy, the interaction energy with nuclei, and the interaction energy with spatial distribution of the electrons, employs one adjustable parameter. This parameter takes into account some redistribution of the electron density in the crystal. The relationship between the method presented and the molecular orbital and pseudopotential methods is discussed. The method is applied to the cases of Sc 2 +, Ti 2+ and Co 2÷ in ZnS, and Co 2+ in ZnSe. The cubic field splitting parameter A and the position of impurity levels with respect to the valence band is calculated within the frame of the one-electron approximation. Maximum free charge in two-phase surface charge-coupled devices. KENNETH BOARD. Solid-State Electron. 19, 715 (1976). The maximum charge that can be stored and transferred efficiently in a surface CCD is significantly larger than in the buried channel device. However, whereas in the three-phase surface CCD the maximum charge depends primarily on clock voltage differences, in the two-phase device it depends on parameters which are fixed during fabrication. It is important therefore in the design of twophase structures, to have a detailed understanding of how this charge depends on device parameters. The implanted barrier (IB) and stepped oxide (SO) structures are analyzed by comparing the surface potentials obtained from onedimensional models of the appropriate regions and a number of contrasting dependences found between the two types of CCD. A further limit to the maximum free charge for both devices is set when the field at the oxide-semi-conductor interface (and normal to it) approaches the breakdown field for Silicon. The presence of the implanted region in the lB. CCD gives rise to a radically different field limitation for the structure. Analytical solutions for the breakdown voltage of abrupt cylindrical and spherical junctions. B. JAYANT BALIGA and SORAa K. GHANDHi. Solid-State Electron. 19, 739 (1976). Analytical solutions for the breakdown voltage of abrupt cylindrical and spherical junctions have been obtained, using suitable approximations for the electric field in the depletion layer. These solutions are shown to be within __1~o of exact computer solutions for doping densities of less than 1016 cm- 1. By normalization to the parallel plane case, these solutions have been presented in a form which allows the computation of the breakdown voltage of both cylindrical and spherical junctions using a single curve for each situation. The interaction of the two-dimensional plasmon with the surface plasmous in an MOS structure. A. CAILLE and M. BANVILLE. Solid-State Commun. 19, 951 (1976). The two-dimensional electron gas in the inversion layer of an MOS structure gives rise to a two-dimensional plasmon, which has