Oriented growth, diamond

Besides the MPCVD reactors, other CVD reactors are also used for diamond deposition. They are hot filament, DC plasma, radio-frequency (rf) plasma, thermal rf plasma, plasma jet, and combustion CVD reactors. In the following, hot filament and DC plasma CVD reactors will be described, because they have been used for oriented growth of diamond. 

Although this monograph is mainly concerned with the oriented growth of diamond films, it would be worthwhile to briefly review the atomic structures of diamond surfaces studied by STM and AFM. In this regard, Ref. [137] is comprehensive and will be very useful. Additional descriptions on surface reconstruction are given in Appendix D. 

After the work of Zhu et al. [166], oriented growth of diamond on Ni(lOO) was studied extensively by Glass and Sitar s groups at North Carolina State University (NCSU), and a three-step process was established to suppress graphite formation by HFCVD [170-172] ... 

A local epitaxy of diamond crystallites has been reported in Ref. [200], where Si(lOO) substrate was pretreated in microwave plasma under conditions of c —0.1%CH4/H2, P= 100-120Torr, and 7 = 1040-1050°C for lOh, and successively, diamond growth was done under conditions of c= 1%CH4/H2, 7 = 50-60 Torr, and 7s = 850-880 °C for 40 h. On the Si substrate, there were two mutually oriented large diamond crystals of 120 x 150 pm in size and a number of small oriented... 

In Ref. [261], a process optimization for oriented diamond nuclei was done using a software for statistical experimental design [262] (design for experimental method). The process parameters for BEN and the oriented growth in the three-step process are listed in Table H.3. The substrate used was Si(lOO), which had been carburized for 3h under the following conditions P = 20Torr, Pm=1000W, 7 s = 900°C, and... 

Effects of Si substrate orientation, (100), (111), and (110), on oriented diamond growth have been studied in Ref [288] (see also Section 11.16). Continuous diamond films with (100) and (111) orientations could be synthesized on Si(lOO) and Si(l 11) substrates, respectively, using the BEN process. The (110)-oriented continuous film was more random in orientation than (100) and (111), but discrete crystallites with (110) orientation were observed, In Ref [289], (100)- and (11 l)-oriented growth was achieved on Si(lOO) and Si(lll), respectively. In the former case, D 100 //Si(100 and D[110]//Si[l 10], while in the latter, D 111 //Si lll and D[Tl0]//Si[Tl0]. Note, however, that both (100)- and (11 l)-oriented growths were possible on Si(lOO) substrates. The FWHMs of polar and azimuthal angles in XPF measurements were 14° and 11-12", respectively, for the (lOO)-oriented film on Si(lOO). On the other hand, they were 8.5° and IT , respectively, for the (111)-oriented film. In this case, a twinning occurred between diamond grains that were oriented in such a way as D 111 // Si 111 and those that were 60" rotated from... 

In the (100) HOD film synthesis, (lOO)-oriented growth is performed after the BEN step under conditions of q 3 (see Section 5.5) so that the film surface consists of pyramid shape diamond grains, most of which are azimuthally (lOO)-oriented. To form (100) faces, the (111) faces of the pyramids must be grown faster than (100) faces using CVD conditions of a l. Consequently, the (111) faces of the pyramids disappear, and the film surface is filled by (100) faces, resulting in an HOD film. More practically, since it is difficult to set up conditions of a = 1 and 3, conditions of a 1.5 and 2.5 are used in the actual experiments. As stated in Section 5.5, growth parameters of c, Tj, and P must be controlled to attain the these a-parameter values. Addition of B, N, and O also influences the a-parameter, as stated before. 

In Ref. [267], a BEN treatment was done using the conditions listed in Table H.3, and consequently, pyramidal particles were deposited on Si(lll) surface. Such a feature had also been observed for diamond deposition on cBN(l 11), and hence this is a common feature for the initial stage of (11 l)-oriented growth. 

For the growth of diamond films the influence of the key parameters on the growth rate, quality, morphology, and orientation of diamond coatings has been studied and presented in previous papers [32,33]. Results can be summarized as follows. 

Paulmier, D Le Huu, T Zaidi, H. Growth and orientation of diamond crystal thin films obtained by the combustion flame method. Surface Sci. 1997, 377-379, 866-870. 

Diamond Epitaxy, Oriented Growth, and Morphology Ehrolution... 

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