Germanium applications

Ra]agopal G, Needs R J, James A, Kenney S D and Foulkes W M C 1995 Variational and diffusion quantum Monte Carlo calculations at nonzero wave vectors theory and application to diamond-structure germanium Phys. Rev. B 51 10 591-600... 

Germanium is very similar to Si, but its band gap is too small for many practical applications. Large crystals of ultra-high-purity Ge have been grown for use as gamma-ray detectors. In such crystals, the net concentration of... 

Not applicable to silicon, germanium, tin, and lead perhydro- is prefixed to the name of the corresponding unsaturated compound. 

Fig. 2 shows one application of ATR depth profiling. In this case, ATR spectra were obtained as a function of angle of incidence from a polymethylmethacrylate (PMMA) film of thickness 0.5 p.m that was deposited onto a germanium hemi-cylinder [4]. The solid line represents the ATR spectrum of PMMA while the squares represent the film thickness that was recovered from the infrared spectra using four different bands. It can be observed that the recovered film thickness was very close to the measured thickness. 

The invention of the germanium transistor in 1947 [I, 2] marked the birth of modem microelectronics, a revolution that has profoundly influenced our current way of life. This early device was actually a bipolar transistor, a structure that is mainly used nowadays in amplifiers. However, logical circuits, and particularly microprocessors, preferentially use field-effect transistors (FETs), the concept of which was first proposed by Lilicnficld in 1930 [3], but was not used as a practical application until 1960 [4]. In a FET, the current flowing between two electrodes is controlled by the voltage applied to a third electrode. This operating mode recalls that of the vacuum triode, which was the building block of earlier radio and TV sets, and of the first electronic computers. 

Silicon is also alloyed with germanium (Si Gei.x) for applications such as heterojunction bipolar transistors and optical emitters... 

A major use of germanium is as an alloy with silicon.P l a SiGe transistor with speed of over 60 GHz can allow as low as 1.5 V operation.[33] Other reported applications are ... 

Although germanium was the original semiconductor material in early experiments and production, it is now rarely used as such but mostly as an alloy with silicon.li l l l Some applications of silicon/ germanium are ... 

The state of the synthetic art in this area, in 1979, is much more satisfactory. During the past decade, several new synthetic developments have occurred such that we are closer to the point where the limitations upon synthesis of trifluoromethyl compounds are related more to stability problems in isolated cases, and are not nearly so much due to lack of widely applicable synthetic techniques. We find ourselves, for example, in a position in 1979 where the germanium compound, Ge(CF3)4, which in the past decade, was considered by many workers to be of insufficient stability to permit isolation, has been prepared by four independent methods and is known to be stable to over 100°C. Many of these new synthetic techniques have emerged from studies conducted in our laboratory at the University of Texas and previously... 

Langmuir-Blodged films have been deposited on many different substrates. The substrates used include different types of glass (such as quartz for UV-visible spectroscopy) CaF2 plates for transmission infrared spectroscopy silicon, germanium, and ZnSe plates for internal reflection infrared spectroscopy. For electrochemical applications, LB films... 

The incorporation of elements as carbon, nitrogen, or germanium, however, leads to material with a low mobility and lifetime of charge carriers. This would limit the application of these alloys, and a large research effort has been undertaken to find ways around this problem. 

Semiconductors. In Sections 2.4.1, 4.5 and 5.10.4 basic physical and electrochemical properties of semiconductors are discussed so that the present paragraph only deals with practically important electrode materials. The most common semiconductors are Si, Ge, CdS, and GaAs. They can be doped to p- or n-state, and used as electrodes for various electrochemical and photoelectrochemical studies. Germanium has also found application as an infrared transparent electrode for the in situ infrared spectroelectrochemistry, where it is used either pure or coated with thin transparent films of Au or C (Section 5.5.6). The common disadvantage of Ge and other semiconductors mentioned is their relatively high chemical reactivity, which causes the practical electrodes to be almost always covered with an oxide (hydrated oxide) film. 

The method of migration polymerization (polyaddition reaction) finds extensive application in the production of silicon-, germanium- and tin-containing hetero-organic polymers 97). 

Silicon photodiodes exhibit maximum sensitivity at about 800 nm and they can be used in the whole visible range however their sensitivity drops by several times at the blue region. Special structures can be made with enhanced blue sensitivity (so-called blue or UV diodes). Germanium photodiodes are capable to detect radiation from 600 nm up to 1700 nm. In telecommunication applications InGaAs elements are widely used. 

Limited studies of the germanium and tin hydride analogs of the silicon hydrides show that they share this ability to function as hydride sources in ionic hydrogenations however, their relatively greater reactivity toward acids appears to restrict their practical applications in organic synthesis.24,25... 

The application of these techniques has led to the discovery of a number of organometallic species of arsenic, tin, and antimony in the marine environment. Germanium has not been observed to form organometallic compounds in nature. Some aspects of the geochemical cycles of these elements which have been elucidated by the use of these methods are discussed. 

Anionic Rearrangement of Organosilicon and Germanium Compounds, 16, 1 Applications of 9mSn Mossbauer Spectroscopy to the Study of Organotin Compounds,... 

The first reported preparation of an organogermanium compound dates back to 1887 when Winkler2 4 synthesized tetraethylgermanium. There has, since that time, been numerous publications describing the preparation of organogermanium compounds. However, they remain primarily of academic interest since a practical application for germanium organyls has yet to be found. 

Since plants used as herb medicines contain high amounts of germanium compounds, the latter have been regarded as having immunopotentiation and antitumour activities. At present, organogermanium compounds are mainly used for medical applications. For example, Ge-132 is well known to have not only an antitumour effect, but also to induce interferon (IFN) production in vivo8. 

Amorphous adsorbents, 1 587-589 for gas separation, 1 631 properties and applications, l 587t Amorphous aluminum hydroxide, 23 76 Amorphous carbohydrates, material science of, 11 530-536 Amorphous carbon, 4 735 Amorphous cellulose, 5 372-373 Amorphous films, in OLEDs, 22 215 Amorphous germanium (a-Ge), 22 128 Amorphous glassy polymers, localized deformation mechanisms in, 20 350-351... 

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