SHARC II is a background-limited 350 µm and 450 µm facility camera for the Caltech Submillimeter Observatory undergoing commissioning in 2002. The key component of SHARC II is a 12×32 array of doped silicon 'pop-up' bolometers developed at NASA/Goddard. Each 1 mm × 1 mm pixel is coated with a 400 Ω/square bismuth film and located λ/4 above a reflective backshort to achieve >75% absorption efficiency. The pixels cover the focal plane with >90% filling factor. At 350 µm, the SHARC II pixels are separated by 0.65 λ/D. In contrast to the silicon bolometers in the predecessor of SHARC II, each doped thermistor occupies nearly the full area of the pixel, which lowers the 1/f knee of the detector noise to <0.03 Hz, under load, at the bath temperature of 0.36 K. The bolometers are AC-biased and read in 'total power' mode to take advantage of the improved stability. Each bolometer is biased through a custom ∼130 MΩ CrSi load resistor at 7 K and read with a commercial JFET at 120 K. The JFETs and load resistors are integrated with the detectors into a single assembly to minimize microphonic noise. Electrical connection across the 0.36 K to 4 K and 4 K to 120 K temperature interfaces is accomplished with lithographed metal wires on dielectric substrates. In the best 25% of winter nights on Mauna Kea, SHARC II is expected to have an NEFD at 350 µm of 1 Jy Hz −1/2 or better. The new camera should be at least 4 times faster at detecting known point sources and 30 times faster at mapping large areas compared to the prior instrument.

Reactive ion etching of crystalline silicon, polysilicon, SIO2, and Si3N4 has been studied in a parallel plate electrode configuration, with and without magnetic confinement, in SF6 gas diluted with varying proportions of 02, N2, H2, and Ar. In order to investigate the contamination from the RF cathode, RIE studies were done with RF cathode covered with aluminum disk as well as with 0.5 cm thick circular quartz plate. The RF frequency used is 13.56 MHz and RF power density varied from 0.1 to 0.4 Wcm -2. Experimental results indicate the following: (i) significant contamination occurs on the etched surface with the aluminum covered cathode, but no detectable contamination occurs with the quartz plate covered cathode, (ii) there are etch rate maxima both for silicon and polysilicon with 02 dilution in the range 10-20 volume percent for aluminum covered cathode; these maxima are more pronounced at higher power levels, (iii) etch rates of silicon and polysilicon are much reduced with O2, N2, and especially H~ dilution in volume proportions >30% at all power levels and irrespective of cathode covers; argon dilution has the least effect on the etch rates; (iv) due to loading effect the etch rates 0 20 40 60 80

No abstract

Multiple-energy H-, He-, and B-ion bombardments were performed to obtain uniform high resistivity over the entire thickness of p-type In0.53Ga0.47As. High resistivity, 580 Ω cm, which is close to the intrinsic resistivity limit of ≊103 Ω cm in InGaAs, is observed. The thermal stability of the high-resistance layers depended upon the mass of the implanted ion. The B-ion-implanted layers maintained high resistivity up to ≊200 °C. Photoluminesence measurements were used to obtain the energy of compensating levels produced by light-ion bombardment.

Silicon surface damage caused by reactive ion etching in fluorocarbon gas mixtures containing hydrogen J. Vac. Sci. Technol. B 9, 34 (1991); 10.1116/1.585787 Radiation damage of gallium arsenide induced by reactive ion etching J. Appl. Phys. 62, 4109 (1987); 10.1063/1.339125Reactive ionetchinginduced damage in silicon using SF6 gas mixtures