Micromachined electron tunneling infrared sensors

The development of an improved Golay cell is reported. This new sensor is constructed entirely from micromachined silicon components. A silicon oxynitride (SiO(x)N(y)) membrane is deflected by the thermal expansion of a small volume of trapped gas. To detect the motion of the membrane, an electron tunneling transducer is used. This sensor detects electrons which tunnel through the classically forbidden barrier between a tip and a surface; the electron current is exponentially dependent on the separation between the tip and the surface. The sensitivity of tunneling transducers constructed was typically better than 10(exp -3) A/square root of Hz. Through use of the electron tunneling transducer, the scaling laws which have prevented the miniaturization of the Golay cell are avoided. This detector potentially offers low cost fabrication, compatibility with silicon readout electronics, and operation without cooling. Most importantly, this detector may offer better sensitivity than any other uncooled infrared sensor, with the exception of the original Golay cell

Uncooled tunneling infrared sensor

An uncooled infrared tunneling sensor in which the only moving part is a diaphragm which is deflected into contact with a micromachined silicon tip electrode prepared by a novel lithographic process. Similarly prepared deflection electrodes employ electrostatic force to control the deflection of a silicon nitride, flat diaphragm membrane. The diaphragm exhibits a high resonant frequency which reduces the sensor's sensitivity to vibration. A high bandwidth feedback circuit controls the tunneling current by adjusting the deflection voltage to maintain a constant deflection of the membrane which would otherwise change deflection depending upon incident infrared radiation. The resulting infrared sensor will meet or exceed the performance of all other broadband, uncooled, infrared sensors and can be miniaturized to pixel dimensions smaller than 100 .mu.m. The technology is readily implemented as a small-format linear array suitable for commercial and spacecraft applications

Herd Book Page

Initiate page in Herd Book, FarmHouse Fraternity, NDS

Herd Book Page

Initiate page in Herd Book, FarmHouse Fraternity, NDS

Herd Book Page

Initiate page in Herd Book, FarmHouse Fraternity, NDS

Motivating Genocide: Indirect Colonial Rule as a Motivator of Genocidal Ideology and Policy

In this study I have explored indirect colonial rule as a motivation of genocide. I use case studies of the 1994 Rwandan and 1975 Cambodian genocides to illustrate the way that indirect colonially rule divided societies, creating colonially relegated and colonially elevated sections of society. Genocide becomes a more likely possibility if the colonially relegated group gains power after decolonization. If this group does gain power, it will pursue a policy of retribution for oppression suffered during the colonially period, repression of the colonially elevated group, and minimization of the return to the colonially order in which they were the relegated group. Under the right conditions, these divisions can result in genocide

The U center in potassium bromide crystals

The optical bleaching of the U band in potassium bromide crystals at 78°K has been investigated. The nature of the secondary bands, the U' and the Ul bands, was studied. The U' band consisted of component bands, including the a band which is due to exciton transitions near a negative ion vacancy. One component of the U' band is bleached readily in either of two ways: either by warming the crystal to lo6°K or by irradiating with monochromatic light in the Ul band. This component of the ut band was interpreted as due to exciton transitions near a negative ion vacancy perturbed by the proximity of a Ul center, that is, an interstitial hydride ion. The spectral distribution of quantum efficiency for conversion of U centers to negative ion vacancies at 78°K was measured and found to decrease by 4~ on the high energy side of the U band. The U band has a high energy shoulder and it is suggested that this high energy shoulder exhibits a lower quantum efficiency for the conversion than does the main U band.U of I OnlyThesi