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Silicon and surface-channel SiGe p-metal-oxide-silicon field-effect transistors (p-MOSFETs) using a ZrO2 gate dielectric with equivalent oxide thickness (EOT) less than 20 A was fabricated. These p-MOSFETs show similar behavior to that of other high-k gate dielectric p-MOSFETs reported in the literature, and mobility enhancement is observed in the surface-channel SiGe p-MOSFETs.

ZrO2 thin film has been studied as an alternative gate dielectric. It was deposited directly on a Si substrate by reactive sputtering. An equivalent oxide thickness of less than 11 A with a leakage current of 1.9×10−3 A/cm2 at −1.5 V relative to the flat band voltage has been obtained. Well-behaved capacitance–voltage characteristics with an interface state density of less than 1011 cm−2 eV−1 and no significant frequency dispersion have been achieved. Excellent reliability properties (e.g., low charge trapping rate, good time-dependent dielectric breakdown, low stress-induced leakage current, and high dielectric breakdown) have also been obtained.

Zirconium silicate (ZrSixOy) films have been sputtered by comagnetron-reactive sputtering. The composition of ZrSixOy has been controlled by adjusting the sputtering powers of Si and Zr targets to achieve various effective dielectric constants. The sputtered silicate layers showed low equivalent oxide thickness of 14.5 A with a low leakage of 3.3×10−3 A/cm2 at −1.5 V relative to flat band voltage. The silicate films also exhibited good high-temperature stability and smooth interfacial properties on silicon substrate.

We report the electrical properties of a high dielectric constant (high-k) material, ZrO2, deposited directly on SiGe, without the use of a Si buffer layer or a passivation barrier. ZrO2 thin films of equivalent oxide thickness (EOT) down to 16.5 A were deposited on strained SiGe layers by reactive sputtering. Results indicate that ZrO2 films on SiGe have good interfacial properties and low leakage currents. Sintering in forming gas at 350 °C for 1 h could further improve the film quality. Although threshold voltage stability and dielectric dispersion become a concern for thick ZrO2 films, thin ZrO2 films of EOT less than 20 A exhibit excellent electrical properties making them a good candidate for SiGe applications.

Effects of interfacial layer growth on reactively sputter-deposited TiO2 films were studied. Leakage current was reduced to 10−8 A/cm2 at +1 V after annealing in oxygen ambient and showed tunneling-like temperature dependence. As the interfacial layer grew, interface states and hysteresis were improved significantly. However, the reliability was degraded as the annealing temperature increased.

CaS, with a direct bandgap of 5.38 eV, is expected to be a strong candidate as the active-layer of high performance solar-blind UV photodiodes that have important applications in both civilian and military sectors. Here, we report that a seed-layer-assisted growth approach via molecular beam epitaxy can result in high crystalline quality rocksalt CaS thin films on zincblende GaAs substrates. The Au/CaS/GaAs solar-blind photodiodes demonstrated , more than five orders in its visible rejection power, a photoresponse of 36.8 mA/w at zero bias and a corresponding quantum efficiency as high as 19% at 235 nm.