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Oxide barriers on GaAs by neutralized ion-beam sputtering
Classified abstracts 3418-3429 resolved by taking into account the differences concerning the film orientations. (Germany) W Keune et al, J Appl Phys, 48 (7), 1977,2976-2979. 30 3418. Optid properties of arc-evaporated carbon fdm9 between G and 3.8 eV. (USA) Ellipsometric measurements have been performed at room temperature on arc-evaporated carbon films between 0.6 and 3.8 eV. Previously published data on evaporated carbon films are reviewed and a comparison made between the present data and those for glassy carbon over the same energy range. ET Arakawa et al, J ApplPhys, 48 (7), 1977,317~3177. 30 3419. Free-standiag microdisk targets for single beam laser experiments. (USA) This note describes a simple, inexpensive, but very effective method of producing free-standing microdisk targets for single beam laser experiments. Aluminum targets 100 pm in diameter with thicknesses of I-10 pm have been produced in batches of 2500, having a maximum variation in thickness of less than 10 %. J Varon, Rev Sci Instrum, 48 (7), 1977,941-942. 30 3420. Surface-acoustic-wave film thickness monitor. (USA) The construction and performance of a new type of quartz crystal 6lm thickness monitor which operates on the principles of the surface-acoustic-wave oscillator is discussed. It is shown that this monitor has a number of advantages over the conventional quartz crystal thickness monitor: it has high sensitivity and resolution, the sensor can be reconditioned and it needs no water cooling. There remain, however, some calibration problems. (Israel) S Kovnovicb and E Harnik, Rev Sci Instrum, 48 (7), 1977,920-922. 30 3421. Conductivity and Hall coefficient of graded-composition epitaxial CdJ-lgl -,Te layers. (Germany) On a monocrystalline CdTe substrate epitaxial Cd,Hg,-,Te films were grown in a closed ampoule evacuated to 10d5 torr by condensing HgTe from the gaseous phase under isothermal conditions. Electrical conductivity and Hall voltage of the layers were measured within the temperature range of 77°K to 450°K. (Poland) J M Pawliiowski and P Be&, Phys Stut Sol (a). 32 (2), 1975,63%646. 30 3422. Electron microscopy studies of the alloying behaviour of Au on GAS. (Germany) Single crystal GaAs samples with gold films of thicknesses in the range 400 to 4500 A, deposited in a vacuum of lo-’ torr, have been alloyed at 550°C in vacuum for variable periods of time. Transmission electron microscopy has shown that alloying Au films on GaAs produces several distinct damage zones within the substrate. The first zone includes a heavily disordered region, which increases in lateral extent as a function of initial film thickness and alloying duration. The second region is characterized by the presence of hexagonal AuGa, dislocation lines and Au precipitation. The third zone contains a high density of dislocation lines extending to depth in excess of 3000 A. In samples containing thin Au films and alloyed for short periods, amorphous regions are absent and the formation of AuGa is less extensive. (USA) T J Magee and J Peng, Phys Sfat Sol (II), 32 (2), 1975,695-700. 31. SPUTTERING 31 3423. Oxide barriers on GaAs by neutralized ion-beam sputtering. (USA) Tantalum and silicon oxides have been sputter deposited onto gallium arsenide using a 500 eV beam of neutralized argon atoms. MIS devices show very low leakage and capacitances that can be varied from full accumulation to depletion with the application of modest voltages. Other measurements (breakdown field, dielectric constant, adherence, Auger profile and photoluminescence) also suggest that these structures hold potential usefulness for insulatedgate GaAs circuitry. L G Meiners et al, J Vuc Sci Technol, 14 (4). 1977,961-963. 31 3424. Sputtering of polycrystalline InP on CdS and other substrates. WSA) Rf sputtering at elevated temperatures was employed to grow poly102
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crystalline layers of InP on various substrates including silica, graphite and crystalline CdS and InP. Grain sizes were generally less than one gm in diameter so that, as now made, these films are probably not suitable for solar cell applications. I P Kamh~ow et al, J Vuc Sci Technol, 14 (4), 1977,1029. 31 3425. Hall effect in amorphous thin-film magnetic alloys. (USA) Amorphous magnetic alloys have unusually large extraordinary Hall coefficients (R,) defined by the ratio of the Hall resistivity to the net magnetic moment of the alloy. We have studied the Hall effect in amorphous films in the ternary ferrimagnetic systems Co-Gd-Mo and Co-Gd-Au. alloys which exhibit compensation temperatures the Hall coefficient R. is oositive and below (T,.,.1. . __...I_ Above T-. TcOmpthe sign of R, changes to negative in a discontinuous manner, probably limited by the homogeneity of the sample. We have also prepared amorphous Gd-Au and Y-Co films and measured R, which we use to qualitatively separate the effects of the Co and Gd sublattices in the ternary alloys. We attribute the sign of R, to a combined effect of a negative Gd and a positive Co Hall coefficient. Above T,,, the Co is dominant and points in the direction of the applied field H while Gd is antiparallel to H. Thus, both sublattices contribute in a positive sense to R,. Below Tcompthe Gd moment is dominant and the sign of R, is reversed for both sublattices. Values of R, up to 25 x 10eg &m/G are measured near TcomDand when MO is present, R, is reduced to 5 x 10sg Slcm/G. Molybdenum is known to cause a strong decrease in the moment of the cobalt sublattice and this probably is the reason R, decreases. Our interpretation of the Hall effect in these ferrimagnetic systems differs from other recently proposed models. T R McCuire et al, J Appl Phys, 48 (7), 1977,2965-2970. 31 3426. A method for determination of thermal conductivity of thin 6lms. (USSR) A method for measurement of thermal conductivity of thin lihns with thickness ranging from 0.1 to 50 pm in vacuum of IO-’ torr is described. The thermal conductivity is determined from thechange in electrical resistance of a resistance heated S-shaped platinum film, deposited by cathode sputtering at a pressure of 5 x lo-* torr on the examined film. Yu A Boykov et al, Prib Tekh Eksper, No 2,1975,230-232 (in Russion). 31 3427. Electrode for high-frequency sputtering. (USSR) Construction of a target-electrode for high-frequency sputtering of dielectrics is described. As the high-voltage coaxial lead is placed outside the vacuum chamber the parasite capacity is reduced and the coefficient of utilization of high-frequency generator is increased. The high-frequency plasma in the interelectrode gap is stable in the range of power of high-frequency generator of 0.1 to 5 kVA. E V Dorosbko and V G Savitskiy, Prib Tekh Eksper, No 1, 1975, 236-237 (in Russion).
32. EVACUATION
AND SEALING
32 3428. Pulse neutron-X-ray tube. (USSR) A sealed-off tube is described, which generates simultaneously neutrons and X-rays. The accelerating tube contains a plasma source of deuterons and a target where reactions T(d, n)4He or D(d, n)3He take place. The accelerating voltage up to 200 kV is used. Secondary electrons, formed at bombardment of the target with ions, are collected on a collector and generate X-rays. Yu G Bessarabskiy et al, Prib Tekh Eksper, No 1, 1975, 211-213 (in Russion). 32 3429. Some characteristics of microchannel plates. (USSR) Basic steady characteristics of microchannel plates with 20, 40 and 100 micron channels are investigated in a vacuum of 2 x 10m6 to 1 x 10m5 torr. The dependences of amplification, resistance and dark current on voltage are measured. The energy distribution of output electrons is obtained. The principal part of electrons possess energy in the range of 5 to 18 eV. There is also a significant group of electrons with energy up to 100 eV. B N Bragin et al, Prib Tekh Eksper, No 1, 1975, 192-195 (in Rwiun).
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crystalline layers of InP on various substrates including silica, graphite and crystalline CdS and InP. Grain sizes were generally less than one gm in diameter so that, as now made, these films are probably not suitable for solar cell applications. I P Kamh~ow et al, J Vuc Sci Technol, 14 (4), 1977,1029. 31 3425. Hall effect in amorphous thin-film magnetic alloys. (USA) Amorphous magnetic alloys have unusually large extraordinary Hall coefficients (R,) defined by the ratio of the Hall resistivity to the net magnetic moment of the alloy. We have studied the Hall effect in amorphous films in the ternary ferrimagnetic systems Co-Gd-Mo and Co-Gd-Au. alloys which exhibit compensation temperatures the Hall coefficient R. is oositive and below (T,.,.1. . __...I_ Above T-. TcOmpthe sign of R, changes to negative in a discontinuous manner, probably limited by the homogeneity of the sample. We have also prepared amorphous Gd-Au and Y-Co films and measured R, which we use to qualitatively separate the effects of the Co and Gd sublattices in the ternary alloys. We attribute the sign of R, to a combined effect of a negative Gd and a positive Co Hall coefficient. Above T,,, the Co is dominant and points in the direction of the applied field H while Gd is antiparallel to H. Thus, both sublattices contribute in a positive sense to R,. Below Tcompthe Gd moment is dominant and the sign of R, is reversed for both sublattices. Values of R, up to 25 x 10eg &m/G are measured near TcomDand when MO is present, R, is reduced to 5 x 10sg Slcm/G. Molybdenum is known to cause a strong decrease in the moment of the cobalt sublattice and this probably is the reason R, decreases. Our interpretation of the Hall effect in these ferrimagnetic systems differs from other recently proposed models. T R McCuire et al, J Appl Phys, 48 (7), 1977,2965-2970. 31 3426. A method for determination of thermal conductivity of thin 6lms. (USSR) A method for measurement of thermal conductivity of thin lihns with thickness ranging from 0.1 to 50 pm in vacuum of IO-’ torr is described. The thermal conductivity is determined from thechange in electrical resistance of a resistance heated S-shaped platinum film, deposited by cathode sputtering at a pressure of 5 x lo-* torr on the examined film. Yu A Boykov et al, Prib Tekh Eksper, No 2,1975,230-232 (in Russion). 31 3427. Electrode for high-frequency sputtering. (USSR) Construction of a target-electrode for high-frequency sputtering of dielectrics is described. As the high-voltage coaxial lead is placed outside the vacuum chamber the parasite capacity is reduced and the coefficient of utilization of high-frequency generator is increased. The high-frequency plasma in the interelectrode gap is stable in the range of power of high-frequency generator of 0.1 to 5 kVA. E V Dorosbko and V G Savitskiy, Prib Tekh Eksper, No 1, 1975, 236-237 (in Russion).
32. EVACUATION
AND SEALING
32 3428. Pulse neutron-X-ray tube. (USSR) A sealed-off tube is described, which generates simultaneously neutrons and X-rays. The accelerating tube contains a plasma source of deuterons and a target where reactions T(d, n)4He or D(d, n)3He take place. The accelerating voltage up to 200 kV is used. Secondary electrons, formed at bombardment of the target with ions, are collected on a collector and generate X-rays. Yu G Bessarabskiy et al, Prib Tekh Eksper, No 1, 1975, 211-213 (in Russion). 32 3429. Some characteristics of microchannel plates. (USSR) Basic steady characteristics of microchannel plates with 20, 40 and 100 micron channels are investigated in a vacuum of 2 x 10m6 to 1 x 10m5 torr. The dependences of amplification, resistance and dark current on voltage are measured. The energy distribution of output electrons is obtained. The principal part of electrons possess energy in the range of 5 to 18 eV. There is also a significant group of electrons with energy up to 100 eV. B N Bragin et al, Prib Tekh Eksper, No 1, 1975, 192-195 (in Rwiun).