deg K and 77 K. This extends the operating range of The compound has been synthesized. The most advanced el effort, carried out at HP masers further into the infrared. Workers at Lincoln Laboratory have observed alarge Associates, is on , avirtual unknown among the III-V compounds. Company has grown shift of the radiation spectrum of incoherent indium- arsenide diodes to shorter wavelengths in a magnetic p and n type boron phosphide and is presently study- field. Here we may have the attractive possibility of a ing injection electroluminescence. Boron-phosphide tunable maser. The emission wavelength can be electroluminescent light emitters indicate a potentially changed by selecting the cavity mode by a magnetic unique combination of optical, electrical, thermal, and mechanical properties. However, their device feasi- field. A gallium-indium-arsenide system is completely bility has not yet been firmly established. This mate- miscible, and the band gap varies continuously with rial still presents technological difficulties yet to be composition. Thus the ground has been laid for overcome according to HPA's E. E. Loebner. fabricating coherent infrared sources. Suitably pro- portioned gallium-indium-arsenide compounds can SILICON CARBIDE cover the entire wavelength range between 0.84 It sic. Here we go back to group IV in the periodic to 1.1 Metallic indium telluride, a Group III-VI com- table. Single crystals of this material with sufficient purity, structural perfection and size have been pound, is a superconductor (see p 52) with a transi- difficult to grow. If we improve the growth problem tion temperature of 2.18 deg K. The critical mag- netic field is about 800 gauss. and get high quality crystals we will be on the road to ahigher degree of stability, than for the III-V com- pounds and can push our operating temperatures up to 500 deg. C. BN. This high-temperature structural material is both Tyco Laboratories reports growth of a crystal a good insulator and a good conductor. Films have (3/8-in. long in the c direction, and about /14 -in. been evaluated extensively at Texas Instruments for square) by the traveling solvent method (TSM). their dielectric properties, and posible application for Advantages of this method were pointed out in 1961. precision r-f electrostatic capacitors. National Carbon This technique is characterized by the movement of has produced 14-in, diameter cylinders of boron a solvent zone though both single and polycrystalline nitride that are 12-in. long. source crystals. Tyco used three systems: a platinum- silicon-carbide, silicon-silicon-carbide and chromium- BORON PH OS PHIDE silicon-carbide. Cleanliness of the surface is said to be critical factor. This development may pave the way BP. HP Associates reports injection electrolumines- for a 10-ampere rectifier, that has been sought for a cence in boron phosphide. Compound is said to have specific application. more favorable temperature dependence than gallium Silicon carbide structures can make low-power arsenide or electroluminescence. injection lasers (ELECTRONICS, Sept. 6, 1963, p 6).

INTERFERENCE- MICROSCOPE MEASUREMENT 1 FRINGE = 2,700 1 RESISTIVITY: 10 4-10 6 OHM-CM

MOBILITY„ue:10-100CM 2/VOLT-SEC

THICKNESS: 0.1- 30p,

TRAP DENSITY: 1014 -10 16 CM-3

THIN FILM properties of cadmium sulfide, interface-microscope measurement on de- posited CdS film through a metal mask (R. Zuleeg and E. J. Senkovitz, Hughes Air- 7 S10--500 -800X craft, Electrochemical Society Symposium, April, 1963) CdS ,-0.8-1»

/ SUBSTRATE I I I I GROUP IL Si Si Si Si c--- "-- c"c' ..."-c'' "-c I I I I I °GROUP zt si si si si si

I I I I AXIS BASIC UNIT cell of cadmium sulfide, a wurtzite structure, prototype of many of the II-VI compounds. It is possible for STRUCTURE of silicon carbide (J. W. I I I I I some II-VI compounds to take a xinc- Faust, Jr. Westinghouse, Silicon Carbide Si Si Si Si Si C C C' C blende III-V structure. (Y. T. Sihvonen, Symposium, Air Force Cambridge Research Texas Instruments) Center, 1959) I I I I

October 25, 1963 electronics 44