Transient response of photoexcited electrons: negative and oscillating current

Time-dependent current of the electrons excited in the conduction band after ultrafast interband photogeneration is studied theoretically. The transient photocurrent is calculated for the nonlinear regime of response to a stationary electric field. The response demonstrates transient absolute negative conductivity when the electrons are excited slightly below the optical phonon energy, while the periodic oscillations of the electric current appear after formation of the streaming distribution. The quenching of these peculiarities by the elastic scattering of electrons is also considered.Comment: 5 pages, 3 figure

Spectral and polarization dependencies of luminescence by hot carriers in graphene

The luminescence caused by the interband transitions of hot carriers in graphene is considered theoretically. The dependencies of emission in mid- and near-IR spectral regions versus energy and concentration of hot carriers are analyzed; they are determined both by an applied electric field and a gate voltage. The polarization dependency is determined by the angle between the propagation direction and the normal to the graphene sheet. The characteristics of radiation from large-scale-area samples of epitaxial graphene and from microstructures of exfoliated graphene are considered. The averaged over angles efficiency of emission is also presented.Comment: 6 pages, 5 figure

Transient magnetoconductivity of photoexcited electrons

Transient magnetotransport of two-dimensional electrons with partially-inverted distribution excited by an ultrashort optical pulse is studied theoretically. The time-dependent photoconductivity is calculated for GaAs-based quantum wells by taking into account the relaxation of electron distribution caused by non-elastic electron-phonon interaction and the retardation of the response due to momentum relaxation and due to a finite capacitance of the sample. We predict large-amplitude transient oscillations of the current density and Hall field (Hall oscillations) with frequencies corresponding to magnetoplasmon range, which are initiated by the instability owing to the absolute negative conductivity effect.Comment: 21 pages, 6 fig

Proceedings of Task Force Meeting "Organizational Structures in Innovation Management", Prague 30 May-3 June, 1983

The papers in this volume are the proceedings of the Task Force Meeting on "Organizational Structures in Innovation Management" held in Prague from 30 May to 4 June, 1983, within the framework of the IIASA Innovation Management Case Study. This study is not primarily the result of IIASA in-house research but is based on collaboration with various organizations from IIASA's National Member Organization (NMO) countries. At present the study has more than 70 collaborators from 17 countries, including 9 international organizations (among them 5 international management organizations), and 14 industrial firms from 9 countries (see Appendix 4). Though there are myriad innovation studies on-going around the world, IIASA has the unique advantage of bringing analysts together in a comparative international setting. The study has been organized as a partial input to a representative final monograph on "Innovation Management in Electrotechnology: Adapting to a Changing Environment". Different issues included in the study are planned to be discussed at separate task force meetings and the proceedings and discussion materials from these meetings will be integrated and used as basic information for a final Vienna conference next year and for preparation of the monograph (see Appendix 5). The first of the above events was held in Leningrad in June 1982 and selected papers from this meeting were published as a IIASA Collaborative Paper CP-83-29. These proceedings are from the second in the series of task force meetings and the program is attached as Appendix 1. This program was used by the participants as a guideline in preparing their papers. A total of 8 countries (4 East and 4 West) were represented by 16 participants from both industry and research. Five Directors from electrotechnical firms were present (from Austria, Bulgaria, Czechoslovakia, Finland and Yugoslavia) delivering papers on the accumulated experience of their companies. Representatives from 5 management organizations, i.e., the Institute of Management in Prague, the Institute for Systems Studies in Moscow, the International Research Institute of Management Sciences in Moscow, and the Department of Business Administration from the University of Gothenburg, also presented papers reflecting the results of their work in the design of management organizational structures. Representatives from 2 additional organizations, the firm "Electrosila" (Leningrad) and the Polytechnical Institute (Leningrad) sent their papers as contributions to the meeting. (For a complete list of participants see Appendix 3). The first report, presented by Prof. Holec, at the first plenary session was a general overview reflecting most of the papers and its object was to describe the trends of development in the organizational structures of the electrotechnical industry. This report helped in focusing the other presentations and discussions on the most important and mutually interesting problems within the framework of organizational structure issues. All other papers are arranged in the same order they were presented at the meeting (see Appendix 2 for the Agenda of the meeting). The discussions are presented in summary form and reflect the character of the productive and creative environment of the meeting. Finally, although we are indebted to many people who contributed towards the success of this meeting, special mention must be made to Helen Vyshinksaya for translating and language editing some of the papers and to Susie Riley who played the crucial roles of administrative assistant, language editor, typist and conscience during all stages of preparation for the meeting and these proceedings