NIRIM-type reactor

Figure 3.1. NIRIM-type reactor with biasing capability.

Growth of diamond on single crystal diamonds with (100) surfaces with off-angles [108] was undertaken using various CH4 concentrations and by a NIRIM-type reactor. The results are shown in Figure 7.4. A smooth surface was obtained for c= 1%CH4/H2 and Ts= 1000°C (see Figure 7.4 (c)). 

It is well known that nitrogen can be easily incorporated in diamond, and usually, it must be very eareful of the air leak in the CVD chamber to prevent nitrogen contamination of diamond films. It is also known that addition of too much nitrogen to the source gas resulted in microcrystalline diamond films rather than well-faceted films. However, Koidl s group found [90] using a NIRIM-type reactor that an addition of small amount of N2 gas to the source gas of c=l-2%CH4/H2 resulted in pronounced (100)-textured films, while the film became microcrystalline without N2 addition. More specifically, an addition of 40-200 ppm of N2 to the... 

The carrier concentrations and hole mobilities in HOD films were measured in Ref. [294]. In this case, B-doped diamond layers of 1.7-pm thickness were simultaneously deposited on a polycrystalline diamond film, an undoped HOD film of roughly 30- im thickness, and a type Ila single crystal (100) using a NIRIM-type reactor. The measured carrier concentrations and the mobilities of the polycrystalline diamond film, the HOD film, and the homoepitaxial layer are shown in Figures 13.3 (a) and (b), respectively. The B concentration determined by SIMS was 4 X 10 cm [294]. Interestingly, the surface of the B-doped layer (deposited on the HOD film) was much smoother than that of the basal HOD film, presumably... 

An uniaxially (lOO)-oriented growth was first found at NIRIM in 1985 (see Ref. [23]). It was intensively studied by Wild et al. [81-83] using a NIRIM-type MPCVD reactor. A SEM image of a (lOO)-oriented film surface is shown in Figure 5.6. It is seen that the (100) faces are co-planar (the angular spread was only 1°), and the... 

Figure 5.16 shows top views of cubo-octahedral diamond particles. The growth rates are calculated separately for a > 3/2 and a < 3/2. The reason for starting with a diamond particle of a = 3/2 is that such particles can be synthesized under the standard conditions of the NIRIM-type MPCVD reactor, i.e. c = 1-2%CH4/H2, P = 30-40 Torr, Ts-SOO C, and = 300 00 W. 

The nucleation density of diamond on as received Si wafer is only in the order of 10 cm by a NIRIM-type MPCVD reactor under standard CVD conditions, e.g. c = 0.5%CH4/H2, P = 30 Torr, and = 800 °C. To make a continuous diamond film within one hour or so under these CVD conditions, a nucleation density of >10 cm is necessary. To achieve this, the Si surface is scratched with diamond powder or paste. The powder size is usually 0.1-30 pm. The nucleation density is increased to approximately 10 cm by this treatment. Alternatively, the Si wafer is ultrasonically treated in alcohol with diamond powder suspension for several minutes. The nucleation density can be increased to 10 -10 cm by this treatment. In both cases, the Si surface is roughened. 

Since the method of BEN was first found by Yugo et al. [3], works of his group till date is first reviewed in the following. The reactor used was a NIRIM-type, as shown in Figure 3.1, where a negative DC bias of Kh = —lOOV was applied to an as received Si substrate with a resistivity of 1-5 - cm and placed on a molybdenum... 

NIRIM-type A microwave plasma CVD reactor developed by National Institute for Research in Inorganic Materials (NIRIM), Japan. This laboratory is now called National Institute for Materials Science (NIMS). 

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