CVD growth

Figure 5.13. Schematic of laser-CVD growth mechanism (stripe deposition).

The conventional method of CVD growth of In-V thin films is to use indium alkyl precursors (Table 8), preferably Me3In. However, early problems in the growth of InP and InGaAs were... 

N3)2Ga N(CH2CH2NEt2)2 ] low volatility Horizontal hot-wall LP-CVD Growth temperature 750-950 °C, preferred orientation of crystallites perpendicular to c-plane of sapphire substrate, no additional N source 287... 

The gas phase is in steady state, because CVD growth processes are slow compared to gas phase dynamics. 

Ellenbecker, M.J. and Wardle, B.L. (2008) Particle exposure levels during CVD growth and subsequent handling of vertically-aligned carbon nanotube films. Carbon, 46 (6), 974—977. 

Apart from the above methods, some of which employ drastic conditions, processes close to equilibrium conditions such as pyrolysis and chemical vapor deposition (CVD) have also been employed to prepare BN nanotubes. The CVD growth of hollow, crystalline BN nanotubules by the pyrolysis of borazine on nickel boride catalyst particles maintained at 1270-1370 K, produced nanotubes with bulbous or flag-like caps (Fig. 38). The reaction is given by,... 

Fig. 3.4 Processes contributing to CVD growth (after Hitchman and Jensen 1993)...

Soga, T., Sharda, T. and Jimbo, T. (2004), Precursors for CVD growth of nanocrystalline diamond. Phys. Solid State, 46(4) 720-725. 

Evans, P., Pemble, M. E. and Sheel, D. W. (2006). Precursor-directed control of crystalline type in atmospheric pressure CVD growth of Ti02 on stainless steel. Chem. Mater. 18(24), 5750-5755. 

The surface roughness of the films is also obtained from ellipsometry. Typical roughness values of 10 A are found for films with optimum CVD growth conditions, while PVD growth conditions lead to a much greater roughness. 

Fig. 2.24. Temperature dependence of the rate of hydrogen evolution in material deposited under different conditions (u) low power CVD growth b) PVD columnar material (c) deposited at room temperature and with a high hydrogen content (Biegelsen et at. 1979).

The dopants also have a catalytic influence on the deposition of the silicon, with the largest effect being induced by boron doping. Under CVD growth conditions, the deposition rate of the silicon increases by about 40% at a boron gas phase concentration of 1 %. Phosphorus doping suppresses the growth rate, but by a smaller amount. Fig. 5.5 shows the growth rates of compensated a-Si H and illustrates both effects. 

Beryllium has few applications in thin-fitm materials, owing to toxicity issues and the generally high air sensitivity of its compounds. Beryllium is a desirable ablator material in fusion research, and beryllium ion is an excellent p-type dopant in compound semiconductors such as InP and (In,Ga)As. There are limited precursors available for the CVD growth of... 

There has been considerable development of precmsors for the CVD growth of group 13 sulfide and selenide semiconductors. Sulfur precmsors that have been reported to date are based upon monothiocarbamato, dithiocarbamato, thiocarboxylato, thiolato, and dialkylselenophosphoryl-amido ligands. In certain cases, selenium analogs of these ligands have been employed to create precmsors for the respective selenide phases. In addition, sulfur and selenium tetramers of the formula [RME]4 have been used as precmsors to metal sulfide and selenide phases, and have shown phase selectivity that appears to correlate with the cubic cores of the... 

The first CVD growth of CdO films was reported only recently by several groups. Low pressure CVD of CdMe2 with molecular oxygen afforded CdO films at substrate temperatures between 150 and 450 °C. Precursors containing hfac ligands include Cd(hfac)2(tmeda), Cd(hfac)2(H20)2, and Cd(hfac)2(dme). ... 

---