Lead selenide (PbSe) nanowires were grown by magnetron sputtering on silicon with silicon dioxide (SiO2/Si) substrates, and characterized by scanning electron microscopy, x-ray diffraction, Fourier transform infrared spectroscopy, photoluminescence, and x-ray photoelectron spectroscopy. Closely packed PbSe nanowires of approximately 100 nm diameter grew in the ⟨111⟩ rock-salt cubic structure orientation. These large wires showed a large blueshift in the luminescence and absorption compared to the bulk crystal, demonstrating quantum confinement. This is attributed to a strong built-in field due to surface states, band bending, and a depletion layer which confines the carrier states.

Cr/Au meander-shaped resistors were fabricated on 0.2 μm thick square-shaped silicon nitride diaphragms with diaphragm dimensions ranging from 0.775 to 2.275 mm. The performance of these sensors was measured in a vacuum chamber as a function of resistor powers from 0.5 to 3 mW at pressures ranging from 2×10−4 to 760 Torr. The lengths of the meander-shaped resistors increase from 5.5 mm for the 0.775 mm diaphragm to 33.6 mm for the 2.275 mm diaphragm devices. It is shown that the pressure dependence of the devices is governed by the kinetic gas theory and that the devices can measure pressures from about 10 to 1×10−3 Torr. At a resistor power of 2 mW at 760 Torr, the 2.275 mm diaphragm device, which has the largest sensing area, exhibits the highest sensitivity.

Using bulk micromachining, meander-shaped resistor elements consisting of 20 nm Cr and 200 nm Au were fabricated on 1 μm thick silicon nitride membranes, bridges, and cantilevers. The resistance change as a function of pressure depends strongly on the thermal resistance of the two metal lines connecting the heated resistor to the silicon bulk (cold junction) and on the thermal resistance of the silicon nitride. Relative resistance changes ranging from about 3% (small membrane) to 20% (bridge) per mW of input power were obtained when operating the devices in constant voltage mode. The pressure where maximum sensitivity of these gauges occurs depends on the distance ‘d’ between the periphery of the heated resistor element and the silicon cold junction. Devices with ‘d’ ranging from 50 μm to 1,200 μm were fabricated. Assuming that pressures can be reliably measured above the 10% and below the 90% points of the resistance versus pressure curve, the range of these devices is about two orders of magnitude. By integrating two devices, one with d = 65 μm and one with d = 1,200 μm on the same chip and connecting them in series, the range can be increased by about a factor of three. By fabricating the cantilever devices so that they curl upon release, it will be shown that these devices also exhibit larger range due to varying ‘d’.

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Cr/Au meander-shaped resistors were fabricated on 200nm thick square silicon nitride diaphragms on silicon with diaphragm dimensions of 0.775mm, 1.025mm, 1.275mm, 1.775mm, and 2.275mm. At 760Torr, the resistors were heated to about 20°C -60°C above ambient by Joules heating and the resistances were monitored as a function of pressure from 760Torr to 2x10 -4 Torr.As expected from kinetic theory, the sensitivity of the gauges shifted from high to low pressure with increasing diaphragm size (distance from the heat source to the cold junction). Measurements were taken at powers ranging from 0.6mW to 6mW. The sensors were applied to measure potential vacuum bursts due to outgassing events in field emitters and to measure the pressure inside of glass capillaries.