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Effect of temperature-dependent band shifts on semiconductor transport properties
656
World Abstracts on Microelectronics and Reliability
Solid-St. Electron. 20, p. 507 (1977). A numerical program to obtain the impurity profile within a semiconductor material from the measured spreading resistance data was developed. In the program, an image method was applied to calculate the spreading resistance of the multilayered structure, which consisted of a stack of layers, each of homogeneous resistivity, with thicknesses equal to the spacing of the spreading resistance data. The solution adopted in the present program is described in this paper. Converting results from the spreading resistance data to the impurity profile of an implanted and diffused sample and buried channel are also shown.
Connection between ESR and electrical conduction in amorphous Si films. S. HASEGAWAand S. YAZAKI. Solid St. Con> mun. 23, p. 41 (1977). A connection between ESR signal and electrical conduction in amorphous Si is investigated. It is suggested that the increase of the spin density with annealing above 400°C is due to partial crystallization, and electrons responsible for ESR are also responsible for the electrical conduction. The validity of Kirkpatrick"s formula for hopping conduction is suggested. Residual lattice absorption in gallium arsenide. HERBERT G. LIPSON, BERNARD BENDOW and STANFORD P. YUKON. Solid St. Commun. 23, p. 13 (1977). The residual lattice absorption of GaAs in the three and four phonon regime is measured over a range of temperatures. The spectra reveal persistent structural features which are interpreted theoretically in terms of phonon density of states effects. Behaviour of amorphous Ge contacts to monocrystalline silicon. H. NORDE and P. A. TORE. Vacuum 27, (3) 20l (1977). The performance of evaporated amorphous Ge films (thickness ~500 A) as contacts to etched n- and p-type silicon crystals of different resistivities are discussed. The Ge was 3 f~cm n-type (p-type was also used but gave no difference), and as external contact to the Ge film an Au layer was evaporated. The behaviour of the aGe-St junction seems to be largely governed by interface effects (and thus depends on surface preparation), as is often the case with metal-St junctions, but Ge gives more reproducible and less time-varying results. In the process of clarifying the function of the contact the following structures were investigated (1) aGe-~,SiIn(Hg), where the latter is an ohmic contact, (2) amSi-~Simetal where amSi is a surface region of the crystal which has been rendered amorphous by ion bombardment, (3) aGe-~,Si-metal. I V and C--V measurements were performed. From the results we conclude that aGe-St junctions act as low-resistance contacts when fed by electon or hole currents from the crystal. The currents (holes and electrons) that are injected into the crystal from the film are limited by barriers to small current densities, usually in the range 10 - 6 A cm -2. It is suggested that the small hole currents are explained by an increase in the hole barrier, effected by positive charges at the interface or in the Ge film, which are built up when positive carriers (holes) are injected by the contact. Investigations of metal contacts to amorphous evaporated Ge films. M. HAFIZ, E. MGBENU, P. A. TOVE, H. NORDE and S. PETERSSON. Vacuum 27, (3) 193 (1977). Amorphous Ge films are used as non-injecting ohmic contacts to highresistivity n-silicon radiation detectors, but the function of this contact is not yet fully explored. One part problem is the role of the metal films used as external contacts to the amorphous film. In this paper we investigate the function of different contacting metals, such as Au, A1, Cr by measuring the l-V-characteristics of sandwich structures with two metals on both sides of the amorphous evaporated Ge film (of typical thickness 1/~m). It was
found that while the symmetric Cr Ge--Cr structure (also Au Ge-Au) had low resistance (leading to resistivity values of ~ 4 × 10'* f2cm for the Ge filmh the unsymmetric structures e.g. AI G e Cr and AI G e Au, showed higher resistance. This was again found for the AI Ge AI structure, which also showed some polarity dependence. Rutherford backscattering was used to investigate diffusion effects between the layers; also the microstructure of the Ge films was investigated by electron microscopy. Depth chemical profiles of MNOS structures measured by AES. J. L1DAY, R. HARMAN and M. VESELY. Vacuum 27, (3) 129 (1977). A review of recent work on measurements of surface and chemical depth profiles of materials of great importance in modern metal oxide and metal nitride oxide semiconductor technology. Characterisation of chemical vapour-deposition processes. Part 1. C. H. J. VAN DEN BREKEL. Philips Res. Rep. 32, 118 (1977). A model on mass transport in chemical deposition processes, based on diffusion in the gas phase and mass transfer at the vapour-solid interface, is presented. From the model emerges the dimensionless CVD number which characterizes the state of the deposition process. In relation to the geometrical shape of the substrate the CVD number gives a criterion for uniform coverage. This criterion should permit a proper selection of process variables. The model is shown to be in qualitative agreement with the observed morphology of polycrystatline silicon layers grown from SiHC13 in H2. Characterisation of chemical vapour-deposition processes Part I1. C. H. J. VAN DEN BREKEL and J. BLOEM. Philips Res. Rep. 32, p. 134 (1977). Mass transport and growth in chemical vapour-deposition processes can be characterized by the dimensionless CVD number as discussed in part I. It is shown there that the same formalism can be applied whether the rate limitation is the mass transport of reactant towards the interface or diffusion of reaction products away from the interface. An important conclusion is that the CVD number not only depends on the deposition temperature but also on the reactant concentration in many cases where reversible reactions are present. This means that increasing the input concentration also changes the value of the CVD number even at temperatures were diffusion-limited reactions are active with all the consequences for the morphology of the resulting layers. Experiments with the growth of polycrystalline silicon from SiHC13 in hydrogen conform the predictions, also morphological observations published by a number of authors can be explained using the model given. Effect of temperature-dependent band shifts on semiconductor transport properties. D. EMIN. Solid St. Commun. 22, p. 409 (1977). A model of a coupled electron-lattice system is utilized as a basis for studying the effect of temperaturedependent shifts of carrier energy levels on the single-band dc conductivity and thermoelectric power formulae. The resulting expressions are not in accord with those which have been previously hypothesized and utilized in analysis of transport data. Research notes: The effect of carrier temperature on the drift induced instabilities in semiconductor plasmas. RAM CHANDRA, Int. J. Electron. 42, (5) 51t (1977). The effect of carrier temperature due to the drifting electric field on the drift-induced instabilities in n-InSb semiconductor plasma is studied. It is found that at 290°K there exists at least one root of the dispersion relation which grows with the frequency for all values of the applied electric field.
World Abstracts on Microelectronics and Reliability
Solid-St. Electron. 20, p. 507 (1977). A numerical program to obtain the impurity profile within a semiconductor material from the measured spreading resistance data was developed. In the program, an image method was applied to calculate the spreading resistance of the multilayered structure, which consisted of a stack of layers, each of homogeneous resistivity, with thicknesses equal to the spacing of the spreading resistance data. The solution adopted in the present program is described in this paper. Converting results from the spreading resistance data to the impurity profile of an implanted and diffused sample and buried channel are also shown.
Connection between ESR and electrical conduction in amorphous Si films. S. HASEGAWAand S. YAZAKI. Solid St. Con> mun. 23, p. 41 (1977). A connection between ESR signal and electrical conduction in amorphous Si is investigated. It is suggested that the increase of the spin density with annealing above 400°C is due to partial crystallization, and electrons responsible for ESR are also responsible for the electrical conduction. The validity of Kirkpatrick"s formula for hopping conduction is suggested. Residual lattice absorption in gallium arsenide. HERBERT G. LIPSON, BERNARD BENDOW and STANFORD P. YUKON. Solid St. Commun. 23, p. 13 (1977). The residual lattice absorption of GaAs in the three and four phonon regime is measured over a range of temperatures. The spectra reveal persistent structural features which are interpreted theoretically in terms of phonon density of states effects. Behaviour of amorphous Ge contacts to monocrystalline silicon. H. NORDE and P. A. TORE. Vacuum 27, (3) 20l (1977). The performance of evaporated amorphous Ge films (thickness ~500 A) as contacts to etched n- and p-type silicon crystals of different resistivities are discussed. The Ge was 3 f~cm n-type (p-type was also used but gave no difference), and as external contact to the Ge film an Au layer was evaporated. The behaviour of the aGe-St junction seems to be largely governed by interface effects (and thus depends on surface preparation), as is often the case with metal-St junctions, but Ge gives more reproducible and less time-varying results. In the process of clarifying the function of the contact the following structures were investigated (1) aGe-~,SiIn(Hg), where the latter is an ohmic contact, (2) amSi-~Simetal where amSi is a surface region of the crystal which has been rendered amorphous by ion bombardment, (3) aGe-~,Si-metal. I V and C--V measurements were performed. From the results we conclude that aGe-St junctions act as low-resistance contacts when fed by electon or hole currents from the crystal. The currents (holes and electrons) that are injected into the crystal from the film are limited by barriers to small current densities, usually in the range 10 - 6 A cm -2. It is suggested that the small hole currents are explained by an increase in the hole barrier, effected by positive charges at the interface or in the Ge film, which are built up when positive carriers (holes) are injected by the contact. Investigations of metal contacts to amorphous evaporated Ge films. M. HAFIZ, E. MGBENU, P. A. TOVE, H. NORDE and S. PETERSSON. Vacuum 27, (3) 193 (1977). Amorphous Ge films are used as non-injecting ohmic contacts to highresistivity n-silicon radiation detectors, but the function of this contact is not yet fully explored. One part problem is the role of the metal films used as external contacts to the amorphous film. In this paper we investigate the function of different contacting metals, such as Au, A1, Cr by measuring the l-V-characteristics of sandwich structures with two metals on both sides of the amorphous evaporated Ge film (of typical thickness 1/~m). It was
found that while the symmetric Cr Ge--Cr structure (also Au Ge-Au) had low resistance (leading to resistivity values of ~ 4 × 10'* f2cm for the Ge filmh the unsymmetric structures e.g. AI G e Cr and AI G e Au, showed higher resistance. This was again found for the AI Ge AI structure, which also showed some polarity dependence. Rutherford backscattering was used to investigate diffusion effects between the layers; also the microstructure of the Ge films was investigated by electron microscopy. Depth chemical profiles of MNOS structures measured by AES. J. L1DAY, R. HARMAN and M. VESELY. Vacuum 27, (3) 129 (1977). A review of recent work on measurements of surface and chemical depth profiles of materials of great importance in modern metal oxide and metal nitride oxide semiconductor technology. Characterisation of chemical vapour-deposition processes. Part 1. C. H. J. VAN DEN BREKEL. Philips Res. Rep. 32, 118 (1977). A model on mass transport in chemical deposition processes, based on diffusion in the gas phase and mass transfer at the vapour-solid interface, is presented. From the model emerges the dimensionless CVD number which characterizes the state of the deposition process. In relation to the geometrical shape of the substrate the CVD number gives a criterion for uniform coverage. This criterion should permit a proper selection of process variables. The model is shown to be in qualitative agreement with the observed morphology of polycrystatline silicon layers grown from SiHC13 in H2. Characterisation of chemical vapour-deposition processes Part I1. C. H. J. VAN DEN BREKEL and J. BLOEM. Philips Res. Rep. 32, p. 134 (1977). Mass transport and growth in chemical vapour-deposition processes can be characterized by the dimensionless CVD number as discussed in part I. It is shown there that the same formalism can be applied whether the rate limitation is the mass transport of reactant towards the interface or diffusion of reaction products away from the interface. An important conclusion is that the CVD number not only depends on the deposition temperature but also on the reactant concentration in many cases where reversible reactions are present. This means that increasing the input concentration also changes the value of the CVD number even at temperatures were diffusion-limited reactions are active with all the consequences for the morphology of the resulting layers. Experiments with the growth of polycrystalline silicon from SiHC13 in hydrogen conform the predictions, also morphological observations published by a number of authors can be explained using the model given. Effect of temperature-dependent band shifts on semiconductor transport properties. D. EMIN. Solid St. Commun. 22, p. 409 (1977). A model of a coupled electron-lattice system is utilized as a basis for studying the effect of temperaturedependent shifts of carrier energy levels on the single-band dc conductivity and thermoelectric power formulae. The resulting expressions are not in accord with those which have been previously hypothesized and utilized in analysis of transport data. Research notes: The effect of carrier temperature on the drift induced instabilities in semiconductor plasmas. RAM CHANDRA, Int. J. Electron. 42, (5) 51t (1977). The effect of carrier temperature due to the drifting electric field on the drift-induced instabilities in n-InSb semiconductor plasma is studied. It is found that at 290°K there exists at least one root of the dispersion relation which grows with the frequency for all values of the applied electric field.