Bernard A. MacIver

Palladium/cadmium‐sulfide Schottky diodes for hydrogen detection

The barrier height of a Pd‐CdS Schottky diode is reported to decrease markedly when exposed to hydrogen. This effect is believed to be due to the decrease in Pd work function. It makes a good simple hydrogen detector (even at 298 °K) over the range 500–5000 ppm H2.

Hydrogen‐sensitive palladium gate MOS capacitors

The C‐V characteristics of palladium gate MOS capacitors change significantly when exposed to an air ambient containing up to 4% hydrogen. From these experiments, it is concluded that these changes are due to the lowering of the palladium work function (by as much as 1 V) brought on by the formation of palladium hydride. Mobile charges in the oxide do not contribute to the observed C‐V shifts brought about by exposure to hydrogen.

Characteristics of trench j-MOS power transistors

The fabrication of trench j-MOS transistors in bulk silicon, so that they can be operated in either a three-terminal or a four-terminal mode, is presented. When the transistors are operated in accumulation mode, the specific on-resistance is 0.8 m Omega -cm/sup 2/. In the four-terminal mode a high transconductance, 290 S/cm/sup 2/, is achieved by manipulating the inversion layer charge. In the three-terminal mode, mixed pentode-triode drain characteristics are exhibited. Response times are comparable to those of a junction FET. These properties make the trench j-MOS transistor attractive for power switching.<<ETX>>

j-MOS transistors fabricated in oxygen-implanted silicon-on-insulator

The j-MOS transistor reported earlier has now been fabricated in silicon-on-insulator (SOI) prepared by oxygen ion implantation. Significant improvements in the drain breakdown voltage and off-state leakage current are attributed to a contoured gate oxide and to the quality of the SOI structure, respectively. The electron mobility in the channel silicon is 910 cm2/V . s and the minority-carrier lifetime is 3 µs. We conclude that the j-MOS transistor in SOI shows promise for controlling moderate power loads, particularly in dielectrically isolated power integrated circuit applications.

A hybrid voltage-variable capacitor

A new voltage-variable tuning capacitor is described. Using conventional fabrication techniques, metal-insulator-semiconductor and p-n junction structures are combined to obtain the high voltage sensitivity and low capacitance tolerances required to tune the AM broadcast band. Other potential applications are cited. A simple theory of operation based on nonequilibrium conditions is given together with experimental verification. Devices fabricated with a 530-A-thick SiO 2 insulator on n/n+epitaxial silicon exhibit capacitance ratios of 15:1 in 14 V with a minimum Q of 170. The reverse current is two orders of magnitude higher than expected. This is attributed to growth defects in the epitaxial layer which give rise to a low minority carrier lifetime τ 0 ∼0.1 µs and a high surface recombination velocity S 0 ∼500 cm/s.