Influence of low lifetime regions on recombination in high lifetime regions of semiconductors

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to map the stepwise temperature distribution of a heated surface. From the color-digitized thermograms the chip temperature rise over the ambient air can be computed with the aid of thermocouple measurements. The color thermograms also help evaluate the thermal resistances of the chip and the ceramic carrier, which are used in the thermoelectric analogical analysis of steady-state heat flow from the chip to the surrounding air under free convection condition. The chip temperature rise as evaluated by the thermoelectric analysis checks reasonably well with the infrared and thermocouple measurements. These two methods have their respective advantages in determining the temperature of integrated-circuit chips.

resistors and CMOS transistor arrays as the circuit elements. The CMOS array can be used to produce either an integrator or an inverting amplifier depending on the power supply voltage. The design equations are very simple and with some modifications, the filter can be used to realize any biquadratic voltage transfer function in a straight-forward manner.

Eight-bit microprocessor aims at control applications. W. E. WICKES. Electronics p. 101 (June 1976). LSI chip uses single power supply, interfaces with any 8-bit bus-oriented TTL-compatible peripherals. Determination of temperature of integrated-circuit chips in hybrid packaging. ER-YUNG YU. IEEE Trans. Parts, Hybrids, and Packaying. PHP-12 (2), 139 (1976). This paper describes an infrared technique and an analogical method to determine the maximum temperature of a beam-leaded integrated-circuit chip, mounted on a ceramic carrier. The infrared technique employs a color thermogram camera 7. S E M I C O N D U C T O R

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Processor family specialises in dedicated control. ALAN WEISSBERGER, JACK IRWIN and Soo NAM KIM. Electronics p. 84 (July 1976). Just one or two chips contain all the microcontroller elements needed in low-speed, highvolume applications like appliances or credit checkers. CIRCUITS,

The configuration-based approach for 3d impurities in palladium and platinum. GWYN WILLIAMS. Solid-State Commun. 19, 821 (1976). It is suggested that the magnitude and variation of the characteristic temperature associated with 1st transition series impurities in Pd and Pt could be interpreted within the framework of configurational phase stability criteria. Td-pyramids in silicon epitaxial layers. H. AHARONI. Vacuum 26 (4/5), 181 (1976). The external shapes of tripyramid defects are summarized and typical shapes, deviations from the typical, and the interactions between tripyramids and stacking faults are described. Two basic types of typical tri-pyramids were observed, one with a single peak, and the other with three peaks. The symmetry of the typical tri-pyramids is three-fold. The angle between the apexes of the three pyramids composing the tri-pyramid is 120". Each of the pyramids composing the tri-pyramid is a single crystal but with crystallographic orientation different from that of the rest of the layer. The deviations consist of amputated tri-pyramids, bi-pyramids and monopyramids, none of which are symmetrical. The layer surface nearest the tri-pyramide is not planar, but distorted. Dash etch was used to reveal stacking faults interacting concentrically with typical tri-pyramids. The dimensions of the tri-pyramid and the stacking fault are proportional to the epitaxial layer thickness. Photographs of interactions among tri-pyramids and stacking faults are obtained by using S.E.M. to obtain high resolution, which reveals finer details in higher magnifications. Traces of SiC or SiO 2 or other foreign materials, together with some basic mechanism, are probably responsible for tri-pyramid formation, They can be prevented by proper treatment of the silicon substrate prior to the layer growth. Photo-thermal probing of Si-SiO2 surface centres--ll. Experiment. R. F. PIERRET and B. B. ROESNER. Solid-State Electron. 19, 593 (1976). The results of photo-thermal probing measurements are presented and interpreted to characterize the Si SiO 2 surface center photoresponse and to provide information relevant to the evaluation of existing surface state models. Data is first presented to indisputably confirm the facts that surface center photoemission had indeed been observed and that the photoresponse could be isolated from competing relaxation mechanisms. The subsequent presentation is devoted primarily to an examination and analysis of photovoltage vs time data characterizing the surface center response. From the analysis it is concluded that two distinct types of surface centers are quasi-continuously distributed in energy over the central portion of the Si band gap, with both types of states

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acting as if they were positioned right at the S-SiO 2 interface. The feature distinguishing the two types of states, referred to as A-states and B-states, is widely different photocapture cross section at any given band gap energy measured photocapture cross sections being on the order of 10-19cm2 and 10-2°cm 2 and 102 for A- and B-states, respectively. B-states, which exhibit the longer photorelaxation time constant, dominate the response in the upper portion of the band gap, while A-states dominate the response below approximately E v + 0.3 eV. Finally, the photocapture cross section of each type of state was found to increase systematically toward the band edges due to a Lucovsky-type energy dependence. Doped silicon oxide as diffusion source. A. CHECIELEWSKA and J. KOSZUR. Electron. Tech. 8 (2), 115 (1975). The paper describes a method of preparing doped silicon oxide layers using the reaction of tetraetoxysilane and phosphorus oxichloride oxidation at 400°C. The layers were examined as possible sources of phosphorus diffusion to silicon. A mathematical model of diffusion in Si-SiO 2 system has been developed. The results of computer calculations of impurity distribution in SiO2 layer have been compared with experimental data and the validity of the assumptions used in the model has been discussed.

On the mechanism of indirect band to band recombination i n germanium electron-hole drops. R. W. MARTIN. SolidState Commun. 19, 373 (1976). The line shape of all three recombination lines of electron-hole drops has been analyzed. The appropriate transition matrix element for the TA-line was found to depend linearly on the momentum of the hole only. The TO-matrix element can be visualized as a mixture of the matrix elements for LA- and TAphonons. Influence of low lifetime regions on recombination in high lifetime regions of semiconductors. B. JAYANT BALIGA and MANUEL L. TORREt
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or comparable to the diffusion length, the effective lifetime is more than a factor of three lower than in the homogeneous case.

Formation of impurity atmospheres in Cu-Ge alloy studies by positron annihilation, P. HAUTOJARVl and A. VEHANEN. Solid-State Commun. 19, 309 (1976). Isochronal annealing of plastically deformed Cu + 5 at.% Ge alloy is studied by positron lifetime and annihilation lineshape measurements. The continuous recovery of the annihilation characteristics below the recrystallization is attributed to the formation of germanium atmospheres around dislocations. Epitaxie par jets moleculaires. J. MASSIES, P. ET1ENNE et N. T. DNH. Revue Technique Thompson-CSF 8 (1). (March 1976). Molecular beam epitaxy is a technique for growing thin single-crystal films, applicable to many compounds: II-VL III-V, IV-VI, etc. Having reviewed its underlying principle, the authors describe the epitaxy reactor built in their laboratory, consisting of an ultra-high vacuum chamber with Knudsen cells as the sources of molecular beams plus analysing and testing apparatus (mass spectrometer, LEED and AES). Results with the epitaxial growth of GaAs are presented. In addition to establishing the conditions for epitaxy, the possibilities opened up for studying the mechanism of crystal growth and surface physico-chemistry are stressed. Photo-thermal probing of Si-SiO 2 surface eentres--l. Theory. R. F. PIERRET. Solid-State Electron. 19, 577 (1976). A detailed theoretical analysis is performed to establish identifiable features of the constant capacitance photovoltage time response resulting from carrier emission within a monochromatically illuminated deeply depleted MOScapacitor maintained at liquid nitrogen temperatures. Generalized photo-voltage relationships are derived for the response associated with surface center photoemission, and specific model dependent predictions arc examined to provide photoresponse insight and a reference framework for further considerations. An evaluation is also made of competing emission processes; namely, thermal emission and bulk center photoemission. Suggested experimental procedures are developed for controlling thermal emission and for detecting the existence of carrier photoemission from bulk centers. Current emission from sandwich metal layers AI-AI203-Au. N. FRIEDMAN and V. VINIKMAN. Vacuum 26 (4/5), 189 (1976). Meed showed in 1960 a possibility of building a cold cathode from layers of metal insulator metal. Such a structure can be exploited as a cold cathode that can also work at high frequencies. By vacuum evaporation through suitable masks on a ceramic substrate, an array of aluminium films was deposited between chrome-gold contacts. The films were anodized by an oxide layer of 100 to 150A. Finally gold films were evaporated. The whole array was connected to a socket parallel to a nickel plate and sealed in high vacuum. The emission and conduction current of the device was measured in DC current and in high frequency. One can conclude that the emission current is much smaller at high frequencies. The fluctuations of the emission current are smaller with the frequency increase, and the cathode life is greater. A production reactor for low temperature plasma-enhanced silicon nitride deposition. RICHARD S. ROSLER, WALTER C. BENZING and JAMES BALDO. Solid-State Tech. p. 45 (June 1976). A production reactor for depositing silicon nitride films at low temperature in a glow discharge plasma is discussed. The reactor utilizes a parallel plate capacitively coupled design to realize uniformity of film growth over an extended wafer area. Data are presented on the influence of principal operational variables upon the rate of film deposition and the refractive index and etch rate of the deposited films.

Stacking faults in silicon epitaxial layers. H. AHARONL Vacuum 26 (4/5), 167 (1976), A summary is given of a few specific causes responsible for the formation of stacking faults in silicon epitaxial layers grown on silicon substrates. From the technical point of view, these causes are associated with the treatment of the substrate before the growth process and with the prevention of penetration of foreign materials into the layer before and while it is growing. The location of the causes are: in the substrate (various defects and foreign materials which exist there before the growth process); in the epitaxial layer (mainly foreign materials which penetrate during the growth process}: and in the interface region at and near the metallurgic junction of the substrate/layer. A brief review of the formation of stacking faults created during the layer growth process is given. In this connection, the subject of crystallographic planes and orientation of the stacking faults which determine its boundaries in respect to the rest of the epitaxial layer is touched upon. Also given is a practical summary of revealing the traces of the stacking faults on the layer surface by chemical etching. The major part of the paper is devoted to two subjects: the various causes responsible for the nucleation and formation of stacking faults and detailed examples of geometrical forms of the traces of the stacking faults on the layer surface. This is done by presenting photographs taken through an optical microscope on epitaxial layer surfaces grown during the research on the (ll 1) silicon substrate. In such cases, the traces of the stacking faults on the layer surface appear as equilateral triangles, lines or various combinations of these. In each case, the connection between the experimental results of defect formation and their causes is given. The control possibilities on the formation, concentration and shape of stacking faults is reviewed. This is done by appropriate treatment of substrate surface both outside the reactor (mechanical and chemical polishing) and within the reactor (etching with H2 and HCI}. Finally, a brief review of the utilization of stacking faults for measurement of the epitoxial layer thickness is summarised. Calculation of lattice dynamical properties from electronic energies. Application to C, Si and Ge. D. J. CHADI and R. M. MARTIN. Solid-State Commun. 19, 643 (1976). It is shown that lattice dynamical properties of insulators can be calculated directly from the electronic band structure using the "special points" method. The shear modulii and zone boundary transverse acoustic phonon frequencies of C. Si and Ge are calculated with no adjustable parameters. with results in reasonable agreement with experiment. Thermal emission rates and activation energies of electrons at tantalum centres in silicon. KENSl MlVATA and C. T. SAH. Solid-State Electron. 19, 61 l (1976). The thermal emission rates and activation energies of electrons trapped at the two Ta donor centers in n-type silicon are determined from transient capaciitance measurements on Schottky barrier diodes made on phosphorus and tantalum doubly doped silicon crystals. The thermal activation energies arc 232 and 472 meV for the two donor levels below the conduction band edge and the pre-exponential factors, A. are both 1.5 x 10~°sec ~ in the Ahrrenius equation for the emission rate. A(T/300): exp (-AE/k~T). inSb-diffused junction diodes. M. L. KORWIN-PAWLOWSKI and E. L. HEASELL Electron Tech. 8 (2), 31 0975). The fabrication of p-n junction diodes on p- and n-type InSb by diffusion from the gas phase is described and the characteristics of the diodes analyzed. The impurity diffusion masking capability of thin oxide layers in InSb was in vestigated. Plasma processing at moderate vacuum. HAROLD A. CLARK. Solid-State Tech. p. 51 (June 1976). In reactive ion etching, semiconductor films are processed in an R.F. field at