- Email: [email protected]
Indirect exchange in semiconductors
lii
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
of which the effect may be understood are diacussed. 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_1150u C) is with divacancies (rn-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, Cut. 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 10960, 1025°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 conductivities of 0. 1-0. 2 W~cm-deg,lower than most binary semiconductors AUIBV. It can be said that on the AfflBWCY 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, ~X = 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 Cut from the loss of the Cu~, fill the trapped vacancies. At the same tfliie the vacancies released from the Cw~centers migrate to the same or similar nuclei ancithere they also acquire Cut 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 ZnSIAs2, ZnGeP2, and CdGeP2 of the group of AIIBIVCY 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, inicrohardness, 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 vartation 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.
Vol. 4, No. 7
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
(Received 12 May 1966)
liii
9. PREPARATION AND PROPERTIES OF SILICON TELLURIDE.
8. RESONANCES MAGNETIQUES DE PETITES PARTICULES DE LITHIUM. C. Taupin (Laboratoire de Physique des Solides Associó an CNRS, Facultd des Sciences
91
-
ORSAY).
Plusieurs etudes par diffraction X out mis en evidence la formation au sein de cristaux de LiF fortement irradWs aux neutrons, de très petites particules me~alliquesde purete~exceptionnelle et de formes et dimensions très varie~es. Un mod~lethe’orique simple permet de pr~vofr plusieurs effets tres particuliers sur lea re’sonances magnótiques de certains de ces amas: raie R. M. N. étroite et sans ‘Knight-Shift’, paramagnetisme suivant une loi de Curie et raies R P E extr~mementfines. Tons ces effets ont ëW verifies en etablissant une correspondance entre, d’une part la structure des échanttllons determinèe des dlagrammes X et d’autre part lespar spectres R P E et RdeMrayons N. D’autre part, nous avons montre’ que la relaxation paramagn~tiquèdes spins électroniques ‘a l’interteur de particules métalliques três pures se produit par un móchanisnie diff~rentde celui propos4 dans des travaux antérieurs. A number of X ray diffraction studies have shown that, in heavily neutron-irradiated LiF crystals, very small metallic particles are formed. These particles of an exceptionally high degree of purity assume a great variety of shape and dimensions. With a simple theoretical model many characteristic effects can be predicted on the magnetude resonances of some of these particles: a narrQw Knight-shift-less NMR spectrum, a Curie-type paramagnetism, and extremely narrow E P R lines. All these effects have been verified by carefully comparing the structure of the samples as given by X ray diagrams and the EPR and NMR spectra.
L. 0. Bailey (Texas Instruments Incorporated, Dallas, Texas). The phase diagram for the silicon-tellurium system has been examined primarily by the methods of thermal analysis and metallographic examination. Only a single compound, Si2 Te3 with an incongruent melting point of 892°C,was found to form in the solid state. The compound SiTe was identified only in the vapor phase. Single phase Si2Te3 was prepared by quenching from the liquid phase and annealing, and by vacuum sublimation of excess Te from samples containing no unreacted Si. Red single crystal platelets of Si2 Te3 were grown by vapor transport in evacuated quartz capsules. Unprotected samples of Si2 Te3 hydrolyzed slowly when in contact with air. Si 2Te3 was found to be a p-type semiconductor with a band gap of 2. 0 eV, an electrical resistivity normally in the 10’ to io~ohm-cm range, a thermal conductivity 3. of 4-5 mw/°C-cm, and a density of 4.5 g/cm (Received 11 April 1966) 10. ORIENTED GROWTH OF SEMICONDUCTORS U HOMOEPITAXY OF GALLIUM ARSENIDE. L. C. Bobb, H. Holloway, K. H. Maxwell, and E. Zimmerman (Scientific Laboratory, Ford Motor Company, Blue Bell, Pa). Gallium arsenide has been grown honioepitaxially using arsenic trichioride and gallium. With optimum growth conditions the epitaxial layers have properties similar to those of goodquality bulk crystals. Comparison between epitaxial and bulk crystals is made in terms of the widths of the X-ray rocking curves and of the characteristics of p-n junctions formed within the epitaxial layers.
(Received 28 March 1966) 11. MELTING AND POLYMORPHISM OF Zn AND Cd3As2 AT HIGH PRESSURES.
Moreover, electronic paramagnetic relaxation inside very pure metallic particles was found to be caused by a surface mechanism different from the one proposed in previous works. (Received 24 March 1966) (Revised 31 May 1966)
3As2
A. Jayaraman, T. R. Anatharaman, and W. Kiement, Jr. (Bell Telephonelaboratories, Incorporated Murray Hill, New Jersey). The melting and solid-solid transitions in Zn3As2 and Cd3As2 have been investigated at pressures up to about 40 ithar by means of differential thermal analysis. For Zn~s2,the melting point decreases from about 1015’~Cat zero pressure
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
of which the effect may be understood are diacussed. 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_1150u C) is with divacancies (rn-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, Cut. 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 10960, 1025°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 conductivities of 0. 1-0. 2 W~cm-deg,lower than most binary semiconductors AUIBV. It can be said that on the AfflBWCY 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, ~X = 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 Cut from the loss of the Cu~, fill the trapped vacancies. At the same tfliie the vacancies released from the Cw~centers migrate to the same or similar nuclei ancithere they also acquire Cut 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 ZnSIAs2, ZnGeP2, and CdGeP2 of the group of AIIBIVCY 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, inicrohardness, 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 vartation 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.
Vol. 4, No. 7
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
(Received 12 May 1966)
liii
9. PREPARATION AND PROPERTIES OF SILICON TELLURIDE.
8. RESONANCES MAGNETIQUES DE PETITES PARTICULES DE LITHIUM. C. Taupin (Laboratoire de Physique des Solides Associó an CNRS, Facultd des Sciences
91
-
ORSAY).
Plusieurs etudes par diffraction X out mis en evidence la formation au sein de cristaux de LiF fortement irradWs aux neutrons, de très petites particules me~alliquesde purete~exceptionnelle et de formes et dimensions très varie~es. Un mod~lethe’orique simple permet de pr~vofr plusieurs effets tres particuliers sur lea re’sonances magnótiques de certains de ces amas: raie R. M. N. étroite et sans ‘Knight-Shift’, paramagnetisme suivant une loi de Curie et raies R P E extr~mementfines. Tons ces effets ont ëW verifies en etablissant une correspondance entre, d’une part la structure des échanttllons determinèe des dlagrammes X et d’autre part lespar spectres R P E et RdeMrayons N. D’autre part, nous avons montre’ que la relaxation paramagn~tiquèdes spins électroniques ‘a l’interteur de particules métalliques três pures se produit par un móchanisnie diff~rentde celui propos4 dans des travaux antérieurs. A number of X ray diffraction studies have shown that, in heavily neutron-irradiated LiF crystals, very small metallic particles are formed. These particles of an exceptionally high degree of purity assume a great variety of shape and dimensions. With a simple theoretical model many characteristic effects can be predicted on the magnetude resonances of some of these particles: a narrQw Knight-shift-less NMR spectrum, a Curie-type paramagnetism, and extremely narrow E P R lines. All these effects have been verified by carefully comparing the structure of the samples as given by X ray diagrams and the EPR and NMR spectra.
L. 0. Bailey (Texas Instruments Incorporated, Dallas, Texas). The phase diagram for the silicon-tellurium system has been examined primarily by the methods of thermal analysis and metallographic examination. Only a single compound, Si2 Te3 with an incongruent melting point of 892°C,was found to form in the solid state. The compound SiTe was identified only in the vapor phase. Single phase Si2Te3 was prepared by quenching from the liquid phase and annealing, and by vacuum sublimation of excess Te from samples containing no unreacted Si. Red single crystal platelets of Si2 Te3 were grown by vapor transport in evacuated quartz capsules. Unprotected samples of Si2 Te3 hydrolyzed slowly when in contact with air. Si 2Te3 was found to be a p-type semiconductor with a band gap of 2. 0 eV, an electrical resistivity normally in the 10’ to io~ohm-cm range, a thermal conductivity 3. of 4-5 mw/°C-cm, and a density of 4.5 g/cm (Received 11 April 1966) 10. ORIENTED GROWTH OF SEMICONDUCTORS U HOMOEPITAXY OF GALLIUM ARSENIDE. L. C. Bobb, H. Holloway, K. H. Maxwell, and E. Zimmerman (Scientific Laboratory, Ford Motor Company, Blue Bell, Pa). Gallium arsenide has been grown honioepitaxially using arsenic trichioride and gallium. With optimum growth conditions the epitaxial layers have properties similar to those of goodquality bulk crystals. Comparison between epitaxial and bulk crystals is made in terms of the widths of the X-ray rocking curves and of the characteristics of p-n junctions formed within the epitaxial layers.
(Received 28 March 1966) 11. MELTING AND POLYMORPHISM OF Zn AND Cd3As2 AT HIGH PRESSURES.
Moreover, electronic paramagnetic relaxation inside very pure metallic particles was found to be caused by a surface mechanism different from the one proposed in previous works. (Received 24 March 1966) (Revised 31 May 1966)
3As2
A. Jayaraman, T. R. Anatharaman, and W. Kiement, Jr. (Bell Telephonelaboratories, Incorporated Murray Hill, New Jersey). The melting and solid-solid transitions in Zn3As2 and Cd3As2 have been investigated at pressures up to about 40 ithar by means of differential thermal analysis. For Zn~s2,the melting point decreases from about 1015’~Cat zero pressure