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Cu-doubling effect in gallium arsenide
Solid State Communications Vol. 4, pp. li
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liv, 1966. Pergamon Press Ltd. Printed in Great Britain.
Abstracts of Articles to be Published in the Journal of the Physics and Chemistry of Solids “J. Phys. Chem. Solids (to be published)” should be cited in references to material quoted from this section prior to the publication of the relevant article.
1. ELECTRON HOPPING TRANSPORT AND TRAPPING PHENOMENA IN ORTHORHOM~IC SULPHUR CRYSTALS. D. J. Gibbons and W. E. Spear (Physics Dept., University of Leicester, Leicester, England). A detailed investigation of the temperature dependence of the electron transport in orthorhombic S crystals has been carried out using drift mobility techniques. The transport is an activated process leading to a drift 2 sec1 v~mobility at 21” Cof (6.2 * 0.6)x 10~ cm and an activation energy of 0. 167 ±0. 005 ev in all principal directions. The remarkable consistency of the results for about 30 specimens, which is in complete contrast to the hole mobility results, allows us to exclude a trap controlled transport. It is suggested that electron conduction in S is an intermolecular hopping mechanism. The results have been fitted to the small po]aron theories of Holstein and of Yamashita and Kurosawa, leading to a polaron binding energy of 0.48 ev. It is likely that the electron interacts Predominantly with fundamental vibrational modes of the S-molecule between 151 cm’ and 236 cm ~ Electron lifetimes with respect to deep centres have been measured by interrupting
National Research Council, ~tawa,
Canada).
The mass magnetic susceptibility (~) of polycrystalline samples of Ag and Au has been determined in the range 6.3000 K by a highprecision Faraday method. Samples with purities ranging to 6N have been measured. It is shown that the observed temperature dependence of X for the lB metals in the range 6-1000°K can be explained in terms of the change in the density of states at the Fermi level produced as a result of the change in the lattice parameter.’ (Received 26 April 1966)
3. DISPERSION STUDIES OF IONIC CRYSTALS WITH LAYER STRUCTURES. M. R. Tubbs (School of Physics, University of Warwick). This paper describes some interferences methods for determining the refractive indices and dispersion curves of small uniaxial crystals. The variations of ordinary and extraordinary refractive indices with wavelength have been measuredfor the particular cases of Cd1 2 and FbI2 the results are analysed to give the position of the absorption edge and the magnitude of the oscillator strength and long wave refractive indices for these materials.
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transits at various depths within the specimen. Bulk lifetimes of up to 17 msec were observed at room temperature. The electron trapping spectrum has been studied by thermally stimulated current measurements and by an electron beam probing technique. Five prominent centres were found and it is shown that the measurements are consistent with the interpretation of electron transport.
(Received 25 March 1966) 4. Cu-DOUBLING EFFECT IN GALLIUM ARSENIDE. C. S. Fuller and K. B. Wolfstirn (Bell Telephone Laboratories, Incorporated Murray Hill, New Jersey).
(Received 7 March 1966) (Revision 16 May 1966) 2. THE MAGNETIC SUSCEP1’IBILJTY OF SILVER AND GOLD IN THE RANGE 6-300°K. C. M. Hurd (Division of Applied Chemistry,
A review of the experimental results pertaming to the “Cu doubling effect” reported previously is presented and models by means ii
lii
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
of which the effect may be understood are discussed. A mechanism based on the assumption that a defect or impurity exists in all GaAs crystals so far examined and which achieved rapid temperature equilibrium with the crystal or a distributed phase in the crystal is in best accord with the resultS. According to this model, doublinginvolves the following processes: (1) InitIal reaction of Cu (700-1150” C) is with divacancies (UI-V divacancies are preferred but Ill-UI divacancies fit the observations almost equally well). This reaction forms Cu(ja. centers and releases vacancies which are maintained in equilibrium by Cu interstitial species, Cuj. At the same time, a defect or tmpurity, I, equilibrates independently to provide a temperature dependent conc, Nj.
Vol. 4, No 7.
temperature dependence of electrical properties. It was found that the melting points of ZnStAs2, ZnGeP~and CdGeP2 lie at 1096°, 10250 and 800° C, respectively, and ZnGeP3 undergoes a solid state transformation at 952°C. CdGeP2 was determined to have the chalcopyrtte structure with the lattice constants of a = 5. 740 ~ 0. OO1A and c/a = 1. 876 ~ 0. 001. All the compounds show total thermal conductivitles of 0. 1-0. 2 W~cm-deg, lower than most binary semiconductors AUIBV. It can be said that on the AIIIBWCY compounds of the same type exists between the shortest interatomic distance and the hardness or the energy gap, and between the tetragonality and the ordering factor, ~y £X(~y ~ = the differences in the ionic radii of cations, ,SX = the electronegativity difference of the constituents). (Received 28 February 1966)
(2) On quenching, each I species in solution traps a vacancy, the excess vacancies, if any, being lost to clusters. (3) Cu1 from a newly applied external phase, together with Cu1 from the loss of the Cu~, fill the trapped vacancies. At the same tfliie the vacancies released from the Cu~ centers migrate to the same or similar nuclei ancithere they also acquire Cu1 atoms. The final state, after all vacancies are filled, results In doubling of the initially diffused Cu. (Received 28 March 1966) (Revised 26 May 1966) 5. THE PREPARATION AND PROPERTIES OF ZnSIAs2, ZnGeP3, AND CdGeP2 SEMICONDUCTING COMPOUNDS* K. Masumoto, S. Isomura and W. Goto (National Research Institute for Metals, Meguro-ku, Tokyo, Japan). Good crystals of ZnStAs2, ZnGeP2, and CdGeP2 of the group of AUBWCY compounds have been grown by either vertical Bridgman method or slow cooling. Preparation of the phosphides was carried out with an internal heating high-pressure resistance furnace. The following physical and electonic properties of these compounds were measured the melting point, lattice constants, microhardness, Seebeck coefficient and thermal conductivity at room temperature, and the temperature dependences of resistivity and Hall coefficient. ZnS1As~and ZnGeP2 are p-type, and CdGeP3 is n-type. ZnS1As3 Is regarded as a similar material to the ‘semi-insulating’ GaAs from the
6. ANELASTIC AND DIELETRIC LOSS IN YTTRIUM-DOPED CALCIUM FLUORIDE. P. D. Southgate (UT Research Institute, Chicago, Illinois). A small anelasttc loss peak appears in yttrium-doped calcium fluoride, being in the kilocycle range at 350°C. Its location is dependent on specimen orientation, and the variation is consistent with the expected behaviour of elastic dipoles formed from interstitial fluorine bound to the yttrium in nn or nnn positions. The activation energy of motion is 1. 2 ± 0. 1 eV. Dieletric losses are dominated by the DC conductivity, which has an activation energy of 1.16 eV. The hypothesis that the primary charge carrier may be the interstitial fluorine ion is discussed. (Received 4 February 1966) (Revised 19 May 1966) 7. INDIRECT EXCHANGE IN SEMICONDUCTORS. James F. Janak (IBM Watson Research Center Yorktown Heights, New York 10598). Indirect exchange of the Ruderman- Kittel type is discussed for donor and conduction elec-’ trons in a semiconductor. It is found that the indirect exchange no longer shows the spatial oscillations characteristic of metal, and is increased in magnitude, though limited spatially to the size of the wavefunction, when the electrons are localized on nonoverlapping donors. The indirect exchange is much too small in magnitude to lead to ferromagnetism in either extrinsic or intrinsic semiconductors.
-
liv, 1966. Pergamon Press Ltd. Printed in Great Britain.
Abstracts of Articles to be Published in the Journal of the Physics and Chemistry of Solids “J. Phys. Chem. Solids (to be published)” should be cited in references to material quoted from this section prior to the publication of the relevant article.
1. ELECTRON HOPPING TRANSPORT AND TRAPPING PHENOMENA IN ORTHORHOM~IC SULPHUR CRYSTALS. D. J. Gibbons and W. E. Spear (Physics Dept., University of Leicester, Leicester, England). A detailed investigation of the temperature dependence of the electron transport in orthorhombic S crystals has been carried out using drift mobility techniques. The transport is an activated process leading to a drift 2 sec1 v~mobility at 21” Cof (6.2 * 0.6)x 10~ cm and an activation energy of 0. 167 ±0. 005 ev in all principal directions. The remarkable consistency of the results for about 30 specimens, which is in complete contrast to the hole mobility results, allows us to exclude a trap controlled transport. It is suggested that electron conduction in S is an intermolecular hopping mechanism. The results have been fitted to the small po]aron theories of Holstein and of Yamashita and Kurosawa, leading to a polaron binding energy of 0.48 ev. It is likely that the electron interacts Predominantly with fundamental vibrational modes of the S-molecule between 151 cm’ and 236 cm ~ Electron lifetimes with respect to deep centres have been measured by interrupting
National Research Council, ~tawa,
Canada).
The mass magnetic susceptibility (~) of polycrystalline samples of Ag and Au has been determined in the range 6.3000 K by a highprecision Faraday method. Samples with purities ranging to 6N have been measured. It is shown that the observed temperature dependence of X for the lB metals in the range 6-1000°K can be explained in terms of the change in the density of states at the Fermi level produced as a result of the change in the lattice parameter.’ (Received 26 April 1966)
3. DISPERSION STUDIES OF IONIC CRYSTALS WITH LAYER STRUCTURES. M. R. Tubbs (School of Physics, University of Warwick). This paper describes some interferences methods for determining the refractive indices and dispersion curves of small uniaxial crystals. The variations of ordinary and extraordinary refractive indices with wavelength have been measuredfor the particular cases of Cd1 2 and FbI2 the results are analysed to give the position of the absorption edge and the magnitude of the oscillator strength and long wave refractive indices for these materials.
.
transits at various depths within the specimen. Bulk lifetimes of up to 17 msec were observed at room temperature. The electron trapping spectrum has been studied by thermally stimulated current measurements and by an electron beam probing technique. Five prominent centres were found and it is shown that the measurements are consistent with the interpretation of electron transport.
(Received 25 March 1966) 4. Cu-DOUBLING EFFECT IN GALLIUM ARSENIDE. C. S. Fuller and K. B. Wolfstirn (Bell Telephone Laboratories, Incorporated Murray Hill, New Jersey).
(Received 7 March 1966) (Revision 16 May 1966) 2. THE MAGNETIC SUSCEP1’IBILJTY OF SILVER AND GOLD IN THE RANGE 6-300°K. C. M. Hurd (Division of Applied Chemistry,
A review of the experimental results pertaming to the “Cu doubling effect” reported previously is presented and models by means ii
lii
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
of which the effect may be understood are discussed. A mechanism based on the assumption that a defect or impurity exists in all GaAs crystals so far examined and which achieved rapid temperature equilibrium with the crystal or a distributed phase in the crystal is in best accord with the resultS. According to this model, doublinginvolves the following processes: (1) InitIal reaction of Cu (700-1150” C) is with divacancies (UI-V divacancies are preferred but Ill-UI divacancies fit the observations almost equally well). This reaction forms Cu(ja. centers and releases vacancies which are maintained in equilibrium by Cu interstitial species, Cuj. At the same time, a defect or tmpurity, I, equilibrates independently to provide a temperature dependent conc, Nj.
Vol. 4, No 7.
temperature dependence of electrical properties. It was found that the melting points of ZnStAs2, ZnGeP~and CdGeP2 lie at 1096°, 10250 and 800° C, respectively, and ZnGeP3 undergoes a solid state transformation at 952°C. CdGeP2 was determined to have the chalcopyrtte structure with the lattice constants of a = 5. 740 ~ 0. OO1A and c/a = 1. 876 ~ 0. 001. All the compounds show total thermal conductivitles of 0. 1-0. 2 W~cm-deg, lower than most binary semiconductors AUIBV. It can be said that on the AIIIBWCY compounds of the same type exists between the shortest interatomic distance and the hardness or the energy gap, and between the tetragonality and the ordering factor, ~y £X(~y ~ = the differences in the ionic radii of cations, ,SX = the electronegativity difference of the constituents). (Received 28 February 1966)
(2) On quenching, each I species in solution traps a vacancy, the excess vacancies, if any, being lost to clusters. (3) Cu1 from a newly applied external phase, together with Cu1 from the loss of the Cu~, fill the trapped vacancies. At the same tfliie the vacancies released from the Cu~ centers migrate to the same or similar nuclei ancithere they also acquire Cu1 atoms. The final state, after all vacancies are filled, results In doubling of the initially diffused Cu. (Received 28 March 1966) (Revised 26 May 1966) 5. THE PREPARATION AND PROPERTIES OF ZnSIAs2, ZnGeP3, AND CdGeP2 SEMICONDUCTING COMPOUNDS* K. Masumoto, S. Isomura and W. Goto (National Research Institute for Metals, Meguro-ku, Tokyo, Japan). Good crystals of ZnStAs2, ZnGeP2, and CdGeP2 of the group of AUBWCY compounds have been grown by either vertical Bridgman method or slow cooling. Preparation of the phosphides was carried out with an internal heating high-pressure resistance furnace. The following physical and electonic properties of these compounds were measured the melting point, lattice constants, microhardness, Seebeck coefficient and thermal conductivity at room temperature, and the temperature dependences of resistivity and Hall coefficient. ZnS1As~and ZnGeP2 are p-type, and CdGeP3 is n-type. ZnS1As3 Is regarded as a similar material to the ‘semi-insulating’ GaAs from the
6. ANELASTIC AND DIELETRIC LOSS IN YTTRIUM-DOPED CALCIUM FLUORIDE. P. D. Southgate (UT Research Institute, Chicago, Illinois). A small anelasttc loss peak appears in yttrium-doped calcium fluoride, being in the kilocycle range at 350°C. Its location is dependent on specimen orientation, and the variation is consistent with the expected behaviour of elastic dipoles formed from interstitial fluorine bound to the yttrium in nn or nnn positions. The activation energy of motion is 1. 2 ± 0. 1 eV. Dieletric losses are dominated by the DC conductivity, which has an activation energy of 1.16 eV. The hypothesis that the primary charge carrier may be the interstitial fluorine ion is discussed. (Received 4 February 1966) (Revised 19 May 1966) 7. INDIRECT EXCHANGE IN SEMICONDUCTORS. James F. Janak (IBM Watson Research Center Yorktown Heights, New York 10598). Indirect exchange of the Ruderman- Kittel type is discussed for donor and conduction elec-’ trons in a semiconductor. It is found that the indirect exchange no longer shows the spatial oscillations characteristic of metal, and is increased in magnitude, though limited spatially to the size of the wavefunction, when the electrons are localized on nonoverlapping donors. The indirect exchange is much too small in magnitude to lead to ferromagnetism in either extrinsic or intrinsic semiconductors.