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Saturation capacitance of thin oxide MOS structures and the effective surface density of states of silicon
World Abstracts on Microelectronics and Reliability E u e r ~ dimgmeen el eteetmm e*mrilmtlug to the cutout in revet~
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Electron TectmoI. 6,(3/4),.49 (1973). In this paper is considered the energy distribution of electrons emitted from the metal into the semiconductor. The numerical computation is made-using WKB approximation for metal-ntype siliccm junction. Examim~on is made of the influence of the donor impurity concentration, applied voltage and temperature on the distribution. Special attention is devoted to the case of the heavily doped semiconductor. Results of the numerical computation are presented graphically in the form of the dependence of the normafized electron flux emitted from the metal into the semiconductor (n-type Si) as a function of the electron energy.
cnowsr, L
Polarizabitim d shallow donors in silicon. J. B~'mN, T. G. CASTN~ and N. K. L ~ . Solid St. Commun. 14, 1321 (1974). Capacitance measurements on N-type As, P, and Sb-doped Si samples have been made between 4.2 and 1.35°K, from 0"3 to 100 kHz as a function of (N o - NA) ~nigh purity to 2.7 × 101S/cm3]. From the dielectric constant variation with (No - N~) donor polarizahilities %s, up, and % are found respectively to be 1.0 _+ 0.1, 2.4 _ 0-4 and 3.1 + 0'3 × I0 5 A 3. Depmition and Auger analysis of depeldted SIO2 on AlxGa~t_x>As. I. W~SSMAN, G. ANTYPAS, R. GERLACH, V. HOFFM^N and N. TAYLOR, Vacuum 24, 81 (1974). The relevance of Auger analysis to compound device technology is discussed generally and with particular reference to silica on AlxGa~l_x~As. Experimental procedures are described and results given.
Trends in Crystal growing. J. BARRETTand R. H. HELL,JR. Solid St. Technol. 37 (Feb. 1974). The history and structure of crystals are briefly described. The main types of crystalgrowing techniques presently employed are summarized. Crystals of significant commercial and scientific interest are discussed and reasons for using specific growth techniques for particular crystals are presented. Progress in crystalgrowing techniques, from solution through "levitation growth" using the Czochralski method is described. Liquid encapsulated growth of gallium phosphide is discussed in some detail and cited as the most advanced and sophisticated crystal-growing technique in commercial use today. Saturatlen Calmcitam~ of thin oxide MOS structures and the effective ~m,face demity of states of silicon. J. MAS~JIAN, G. ~ N and C. SVeNSSON. Solid St. Electron. 17, 335 (1974). The capacitance vs voltage curve of thin oxide (30-~-40 A) MOS structures in strong accumulation was studied. The results were interpreted in terms of equivalent surface density of state masses, which was found to be 0.2 me for the silicon valence band and 0.06 mo for the conduction band, for both 111 and 100 surfaces. The experimental density of state masses were shown to be much lower than the bulk values. Equivalent density of states masses were calculated from a surface quantization model and in this case agreement with the experiments was obtained for the valence band only. Current muitildieatiou in meUd-tmdiator-semieooductor (MIS) tunnel diodes, M. A. G ~ and J. SHEWCHUN.Solid
449
St. "Electron. 17, 349 (1974). In contrast to thick insulator structures, metal-insulator-semiconductor (MIS) diodes with very thin insulating layers ( < 30 A for the siliconsilicon dioxide system) allow appreciable tunnel current flow between the metal and the semiconductor causing the semiconductor to depart significantly from thermal equilibrium conditions when the diode i s biased. Under such conditions, recent experiments have demonstrated that mnltiplication of minority carrier current can occur in the contact region. This multiplication procem is described in detail by deriving analytical expressions characterizing this process and its dependenoe upon the metal, insulator, and semiconductor parameters for one specific class of diode. Numerical methods are used to investigate the multiplication properties under more general conditions. Solutions obtained by this method indicate that values of the small signal multiplication factor, M, in the range of 102- l0 s can be obtained with appropriately designed diodes. The applications of the multiplication process to a transistor structure and to a photodiode with internal multiplication properties are described briefly. A n~aerical study of fleld-aklod ~ R. Q. P~murr and A. H. MAItSHAK. Solid St. Electron. 17, 257 (1974). A numerical method for determining the effect of the internal electric field on the diffusion of impurity ions in semiconductors is described. The model of the diffusion process is defined by the flux equations, the ¢ontinnity equations and Gauss' law. Due to the complexity~of this model, there is no known analytical solution, However, the system of nonlinear equations is solved numerically using an iteration technique. Diffusion profiles are presented for boron diffusing in silicon at 1100°C for various values of surface concentration Co. These profiles are compared to the complementary error function which is the correct solution neglecting the internal electric field. The impurity profiles are also compared to those Obtained by solving an approximate diffusion equation derived by using the concept of a concentration dependent "effective" diffusion coefficient. It is shown that the influence of the electric field on the motion of the impurities is a strong function of the surface concentration. For high values of Co, the impurity profile becomes exponential. The accuracy of the solutions obtained by solving the approximate diffusion equation depends on both the value of Co and the diffusion time. Moat-etched two-phase charge-coupled devices. P. P. GELB~O~R and C. A. T. S ~ . Solid St. Electron. 17, 301 (1974). A novel technique for fabricating two-phase chargecoupled devices is described. The structure requires only thermally grown SiO2 and makes use of moats etched into the silicon which in conjunction with a single layer metallization achieve small interelectrode spacings and directionality of charge transport. The feasibility of the technique is demonstrated experimentally. The devices fabricated were successfully operated as both digital and analog shift registers. The method described offers certain advantages in ease of fabrication and reliability along with the capability for high speed operation. Synthesis and crystal growth of GaAs and GaP for substrates. A. R. VON NElD^ and J. W. N n ~ s ~ . Solid St. Technol. 90 (1974). A review of common procedures in use for preparation of GaAs and GaP single crystal substrates for device application is presented. The principal techniques for
bimed
--
+
juue~m.
M.
MAt~-
Electron TectmoI. 6,(3/4),.49 (1973). In this paper is considered the energy distribution of electrons emitted from the metal into the semiconductor. The numerical computation is made-using WKB approximation for metal-ntype siliccm junction. Examim~on is made of the influence of the donor impurity concentration, applied voltage and temperature on the distribution. Special attention is devoted to the case of the heavily doped semiconductor. Results of the numerical computation are presented graphically in the form of the dependence of the normafized electron flux emitted from the metal into the semiconductor (n-type Si) as a function of the electron energy.
cnowsr, L
Polarizabitim d shallow donors in silicon. J. B~'mN, T. G. CASTN~ and N. K. L ~ . Solid St. Commun. 14, 1321 (1974). Capacitance measurements on N-type As, P, and Sb-doped Si samples have been made between 4.2 and 1.35°K, from 0"3 to 100 kHz as a function of (N o - NA) ~nigh purity to 2.7 × 101S/cm3]. From the dielectric constant variation with (No - N~) donor polarizahilities %s, up, and % are found respectively to be 1.0 _+ 0.1, 2.4 _ 0-4 and 3.1 + 0'3 × I0 5 A 3. Depmition and Auger analysis of depeldted SIO2 on AlxGa~t_x>As. I. W~SSMAN, G. ANTYPAS, R. GERLACH, V. HOFFM^N and N. TAYLOR, Vacuum 24, 81 (1974). The relevance of Auger analysis to compound device technology is discussed generally and with particular reference to silica on AlxGa~l_x~As. Experimental procedures are described and results given.
Trends in Crystal growing. J. BARRETTand R. H. HELL,JR. Solid St. Technol. 37 (Feb. 1974). The history and structure of crystals are briefly described. The main types of crystalgrowing techniques presently employed are summarized. Crystals of significant commercial and scientific interest are discussed and reasons for using specific growth techniques for particular crystals are presented. Progress in crystalgrowing techniques, from solution through "levitation growth" using the Czochralski method is described. Liquid encapsulated growth of gallium phosphide is discussed in some detail and cited as the most advanced and sophisticated crystal-growing technique in commercial use today. Saturatlen Calmcitam~ of thin oxide MOS structures and the effective ~m,face demity of states of silicon. J. MAS~JIAN, G. ~ N and C. SVeNSSON. Solid St. Electron. 17, 335 (1974). The capacitance vs voltage curve of thin oxide (30-~-40 A) MOS structures in strong accumulation was studied. The results were interpreted in terms of equivalent surface density of state masses, which was found to be 0.2 me for the silicon valence band and 0.06 mo for the conduction band, for both 111 and 100 surfaces. The experimental density of state masses were shown to be much lower than the bulk values. Equivalent density of states masses were calculated from a surface quantization model and in this case agreement with the experiments was obtained for the valence band only. Current muitildieatiou in meUd-tmdiator-semieooductor (MIS) tunnel diodes, M. A. G ~ and J. SHEWCHUN.Solid
449
St. "Electron. 17, 349 (1974). In contrast to thick insulator structures, metal-insulator-semiconductor (MIS) diodes with very thin insulating layers ( < 30 A for the siliconsilicon dioxide system) allow appreciable tunnel current flow between the metal and the semiconductor causing the semiconductor to depart significantly from thermal equilibrium conditions when the diode i s biased. Under such conditions, recent experiments have demonstrated that mnltiplication of minority carrier current can occur in the contact region. This multiplication procem is described in detail by deriving analytical expressions characterizing this process and its dependenoe upon the metal, insulator, and semiconductor parameters for one specific class of diode. Numerical methods are used to investigate the multiplication properties under more general conditions. Solutions obtained by this method indicate that values of the small signal multiplication factor, M, in the range of 102- l0 s can be obtained with appropriately designed diodes. The applications of the multiplication process to a transistor structure and to a photodiode with internal multiplication properties are described briefly. A n~aerical study of fleld-aklod ~ R. Q. P~murr and A. H. MAItSHAK. Solid St. Electron. 17, 257 (1974). A numerical method for determining the effect of the internal electric field on the diffusion of impurity ions in semiconductors is described. The model of the diffusion process is defined by the flux equations, the ¢ontinnity equations and Gauss' law. Due to the complexity~of this model, there is no known analytical solution, However, the system of nonlinear equations is solved numerically using an iteration technique. Diffusion profiles are presented for boron diffusing in silicon at 1100°C for various values of surface concentration Co. These profiles are compared to the complementary error function which is the correct solution neglecting the internal electric field. The impurity profiles are also compared to those Obtained by solving an approximate diffusion equation derived by using the concept of a concentration dependent "effective" diffusion coefficient. It is shown that the influence of the electric field on the motion of the impurities is a strong function of the surface concentration. For high values of Co, the impurity profile becomes exponential. The accuracy of the solutions obtained by solving the approximate diffusion equation depends on both the value of Co and the diffusion time. Moat-etched two-phase charge-coupled devices. P. P. GELB~O~R and C. A. T. S ~ . Solid St. Electron. 17, 301 (1974). A novel technique for fabricating two-phase chargecoupled devices is described. The structure requires only thermally grown SiO2 and makes use of moats etched into the silicon which in conjunction with a single layer metallization achieve small interelectrode spacings and directionality of charge transport. The feasibility of the technique is demonstrated experimentally. The devices fabricated were successfully operated as both digital and analog shift registers. The method described offers certain advantages in ease of fabrication and reliability along with the capability for high speed operation. Synthesis and crystal growth of GaAs and GaP for substrates. A. R. VON NElD^ and J. W. N n ~ s ~ . Solid St. Technol. 90 (1974). A review of common procedures in use for preparation of GaAs and GaP single crystal substrates for device application is presented. The principal techniques for