Group II elements

The usual acceptor and donor dopants for Al Ga As compounds are elements from groups II, IV and VI of the periodic table. Group II elements are acceptors and group VI elements are donors. Depending on the growth conditions. Si and Ge can be either donors or acceptor, i.e. amphoteric. This is of special interest in LEDs. 

Group II elements can be seen to follow a pattern very like that found in Group I. Note, however, that the energy required to attain a noble gas configuration is considerably higher indicating that the elements will be less metallic or electropositive in their chemistry (Chapter 6). 

All the Group II elements have two electrons in their outer... 

The Group II elements each have two electrons in their outer energy shells, and the larger ones have an empty shell deep inside them. The transition series added electrons to the inner shell until it was completely filled. So, these last three transition elements are like Group II in construction, with the inner shell filled instead of empty, and two electrons in the outer shell. Those elements with filled shells and those with empty ones are the most stable. 

Also, like the Group II elements, these three metals usually combine by losing two electrons. Thus they form positive ions such as Zn+ 2. 

The structural trends within the group II elements can only be understood by including the influence of the valence-d electrons explicitly through the use of non-local pseudopotentials. This is not unexpected considering our earlier discussion in 5.5 of their densities of states. Figure 6.13 shows the... 

The reaction between additive metals (Ca, Ba, Mg, etc.) and DAP goes to completion and is less dependent of reaction temperature and time. Lead is present in motor oil in a form Chat is physically and chemically different from additive metals. The additive metals are almost exclusively group I and group II elements. Compounds of these elements tend to be more reactive Chan lead compounds and also are more ionic in nature than their lead counterparts. Since lead is not... 

The chemistry of alkyl- and arylaluminum, gallium, indium, and thallium amides has been investigated much more than the comparable chemistry of Group II elements (9,13-18). Alkylaluminum amides especially have a very rich and diverse structural chemistry (9,13-15). When a trialkylalane reacts with primary or secondary amines, the amides 3,3, and 4 are formed in addition to a simple adduct [Eqs. (3) and (4)]. 

Alkhazov et al. (99-101) compared the physicochemical properties and catalytic activities of Group II element molybdates. The calcium, strontium, cadmium, and barium molybdates have a scheelite structure... 

The change in the ionic contribution in the M-O bonding in M(OMe)2 and M(OEt)2 series for the Group II elements is clearly illustrated by the comparison of their IR spectra. It is to be noted that these are the C-H stretching frequencies and not the C-O ones, as one might suppose, that appear to be most sensitive to the electronegativity of metal. Thus from Be to Ba the v(E) Me decrease with nearly 200 cm 1, supposedly due to the induction effect along the M-O-C-H chain [681]. 

Of the organometallic compounds of Group II elements, undoubtedly the chemistry of the magnesium compounds is best known. By contrast, the remaining elements in this group have received less attention and it is only recently that more information on organo derivatives of beryllium and, to lesser extent, of calcium, strontium, and barium has become available. Therefore, most of the observations regarding redistribution equilibria have been of more or less qualitative nature. 

Recently, one more Ti precursor has been introduced, Ti(MPD)(thd)2 (MPD = methyl-pentanedioxide), but its effects on the BST film deposition are not yet well known. It is generally understood that the optimum Ti precursor must have chemical compatibility with the Ba and Sr precursors, such as non-interaction in solution or in the gas phase and similar decomposition characteristics to the Ba and Sr precursors, in addition to volatility. Most of the Ti precursors discussed above have much better volatilities and thermal stabilities than those of the precursors of the group II elements but are still lacking appropriate chemical compatibility with them. It is known that the thermal decomposition of Ti(thd)2(i-0-P )2 is quite different from that of the Ba(thd)2 and Sr(thd)2 from the increasing Ti concentration in the BST film with increasing temperatures.It is believed that the thermal decomposition of Ti(thd)2(i-0-P )2 requires more... 

Thus, the electron affinities of the rare gases, nitrogen, and group II elements are positive but small, and the AEa of the remaining elements should be larger than these. 

There seems to be no absorption study of Cd in silicon. Two Cd acceptor levels have been detected in DLTS investigations of silicon implanted with radioactive mIn transmuting into mCd [107]. However, the case of Cd in silicon seems to be more complex than the other group-II elements as a donor state seemingly associated with substitutional Cd has been identified by ESR under TEC at LHeT [128]. 

Cotton FA, Wilkinson G, eds. 1980. Beryllium and the group II elements Mg, Ca, Sr, Ba, Ra. In Advanced inorganic chemistry A comprehensive text. New York, John Wiley Sons. 

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