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Exciton emission and energy transport in cadmium sulfide crystals
ABSTRACTS ON M I C R O E L E C T R O N I C S AND R E L I A B I L I T Y
319
A practical a p p r o a c h to thln.film circuits, Part L P. L. IfdRsy, Brit. Comm. and Ekctroa., April 1964, p. 2¢2. This first section deals primarily with the relative merits of glass and ceramic substrates used in producing thin-film circuits. Comparison tables are given and the importance of the subatrate is stressed. Micro-circuit geometry is discussed and some methods of pattern production are described in detail. Exciton e m i s s i o n a n d e n e r g y transport in c a d m i u m sulfide crystals. C. E. BLEIL, .7. Phys. Chem. Solids, Vol. 25, 1964, pp. 11-22. It is shown that exciton emission may be used to study detailed energy transport processes in single crystals of cadmium sulfide. The decay time of the exciton emission has been determined to extend from values less than 10 -T sec at 4.2°K to the microsecond range at room temperature. A delay of the exciton emission produced by the transport of energy through the crystal has been observed. The two mechanisms discussed for the explanation of these results are exciton and ambipolar diffusion at room temperature.
MISCELIANXOUS Characteristics o f the dielectric diode a n d triode at v e r y high frequencies. S. BROJDO, SolidState Electron., Vol. 6, 1963, pp. 611-629. The dielectric triode is represented as a one-dimensional parallel-plane model, where the gate electrode consists of a thin continuous equipotential sheet of charge (as in the triode proposed by G. T. Wright). Such a triode is the solid-state analogue of the vacuum pentode with high input and output impedance and operating under conditions of space-chargelimited current. The incremental admittance and transadmittance of the dielectric triode are calculated as functions of transit angle, current density, geometrical dimensions and properties of the material used. The triode in the small-signal mode of operation is represented as a linear active two-port circuit element. The four basic Y parameters of this element are calculated. It is shown that the dielectric triode can operate as a conventional wide-band amplifier up to frequencies of many thousands of megacycles. It is shown also that electronic processes inside the triode do not set the limit for device operation at the frequencies corresponding to the transit angles much larger than ~, and the triode can operate at these frequencies as a tuned amplifier, with the effect of "cold" interelectrode capacitances eliminated. It is concluded that the dielectric triode should considerably extend the u.h.f, limit of operation of transistors and conventional vacuum tubes.
ELECTRON BEAM TECHNOLOGY T h e design o f a n e x p e r i m e n t a l e l e c t r o n b e a m m a c h i n e , P. A. EINSTEIN, D. R. HARVEYand P. J. SIM.XtONS,~r. Sd. Imtrum., Vol. 40, No. 12, December 1963, p. 562. The paper outlines the design of a simple electron beam machine giving an electron spot of a few micrometres diameter. It is shown that the power density achieved approaches closely the theoretical value; in particular a power density of 25 1VIXVcm -2 has been measured in a 2 t~m diameter spot at 60 kV. Examples of some of the initial applications of the machine are also given. Electron b e a m m a c h i n i n g . J. KELLEY,Brit. Comm. Electron., January 1964, p. 20. A high energy beam of electrons can be focused into a small spot, providing a source of extremely high energy density With this source as a tool any material can be cut or drilled. The technique is described and the present state of technology discussed. The theoretical limitations are listed and some applications outlined. R e s e a r c h at R.R.E.mNo. 5. High-speed p r o g r a m m i n g o f an e l e c t r o n b e a m m a c h i n e . T. E. PRICE, Brit. Comm. Electron., January 1964, p. 25. An electron beam machine can be programmed electronically to fabricate a microelectronic system capable of performing a given circuit function. The manner in which the electron beam machine is programmed must be compatible with the speed at which it operates, and it is suggested that a means of producing an accurately positioned array of devices (circuits) directly, without the intermediate drawing and photographic steps, is required. A description of such a proposed system is given in this article.
319
A practical a p p r o a c h to thln.film circuits, Part L P. L. IfdRsy, Brit. Comm. and Ekctroa., April 1964, p. 2¢2. This first section deals primarily with the relative merits of glass and ceramic substrates used in producing thin-film circuits. Comparison tables are given and the importance of the subatrate is stressed. Micro-circuit geometry is discussed and some methods of pattern production are described in detail. Exciton e m i s s i o n a n d e n e r g y transport in c a d m i u m sulfide crystals. C. E. BLEIL, .7. Phys. Chem. Solids, Vol. 25, 1964, pp. 11-22. It is shown that exciton emission may be used to study detailed energy transport processes in single crystals of cadmium sulfide. The decay time of the exciton emission has been determined to extend from values less than 10 -T sec at 4.2°K to the microsecond range at room temperature. A delay of the exciton emission produced by the transport of energy through the crystal has been observed. The two mechanisms discussed for the explanation of these results are exciton and ambipolar diffusion at room temperature.
MISCELIANXOUS Characteristics o f the dielectric diode a n d triode at v e r y high frequencies. S. BROJDO, SolidState Electron., Vol. 6, 1963, pp. 611-629. The dielectric triode is represented as a one-dimensional parallel-plane model, where the gate electrode consists of a thin continuous equipotential sheet of charge (as in the triode proposed by G. T. Wright). Such a triode is the solid-state analogue of the vacuum pentode with high input and output impedance and operating under conditions of space-chargelimited current. The incremental admittance and transadmittance of the dielectric triode are calculated as functions of transit angle, current density, geometrical dimensions and properties of the material used. The triode in the small-signal mode of operation is represented as a linear active two-port circuit element. The four basic Y parameters of this element are calculated. It is shown that the dielectric triode can operate as a conventional wide-band amplifier up to frequencies of many thousands of megacycles. It is shown also that electronic processes inside the triode do not set the limit for device operation at the frequencies corresponding to the transit angles much larger than ~, and the triode can operate at these frequencies as a tuned amplifier, with the effect of "cold" interelectrode capacitances eliminated. It is concluded that the dielectric triode should considerably extend the u.h.f, limit of operation of transistors and conventional vacuum tubes.
ELECTRON BEAM TECHNOLOGY T h e design o f a n e x p e r i m e n t a l e l e c t r o n b e a m m a c h i n e , P. A. EINSTEIN, D. R. HARVEYand P. J. SIM.XtONS,~r. Sd. Imtrum., Vol. 40, No. 12, December 1963, p. 562. The paper outlines the design of a simple electron beam machine giving an electron spot of a few micrometres diameter. It is shown that the power density achieved approaches closely the theoretical value; in particular a power density of 25 1VIXVcm -2 has been measured in a 2 t~m diameter spot at 60 kV. Examples of some of the initial applications of the machine are also given. Electron b e a m m a c h i n i n g . J. KELLEY,Brit. Comm. Electron., January 1964, p. 20. A high energy beam of electrons can be focused into a small spot, providing a source of extremely high energy density With this source as a tool any material can be cut or drilled. The technique is described and the present state of technology discussed. The theoretical limitations are listed and some applications outlined. R e s e a r c h at R.R.E.mNo. 5. High-speed p r o g r a m m i n g o f an e l e c t r o n b e a m m a c h i n e . T. E. PRICE, Brit. Comm. Electron., January 1964, p. 25. An electron beam machine can be programmed electronically to fabricate a microelectronic system capable of performing a given circuit function. The manner in which the electron beam machine is programmed must be compatible with the speed at which it operates, and it is suggested that a means of producing an accurately positioned array of devices (circuits) directly, without the intermediate drawing and photographic steps, is required. A description of such a proposed system is given in this article.