The peak noise voltage for gaAs lumped and distributed models is in the Picovolt domain and is therefore negligible in most applications. In this case, the proposed model is an “open circuit” model that ignores the clutch capacity, as shown in Figure 5.3B. Note from Table 5.2 that the induction of the ground network has no effect on peak noise voltage. This behaviour is due to the resistance of the substrate, which is important enough to seduce the induction of the terrestrial network. The different thin-film deposition methods used for the growth of GaN and other III-V nittrures have a number of advantages in addressing the problems discussed above. The chloride transport process, developed in the late 1960s (Maruska and Tietjen 1969), is characterized by high growth rates that lead to thick films with small concentrations of defects near the open surface and which may be useful as substrate (Molnar 1998). The metal vapour chemical capture process (MOCVD) has been used by Nichia, Inc. to manufacture Nitride III-V LEDs and lasers (Nakamura, 1998) and has some attractive optimization features for the manufacture of these devices (Denbaars and Keller, 1998). The molecular radiation pitaxia (MBE) method has a number of advantages for the study of new materials and, in particular, for the study of epitaxial phenomena, as it is equipped with a series of in situ probes that monitor growth in real time. In addition, the MBE process has become a practical growth method for the manufacture of microwave and optoelectronic devices.
This method has recently been used for the growth of the entire III-V nitrures family and has led to materials with physical properties equivalent to those of the MOCVD method. In this chapter, we present a detailed description of the MBE method used for the growth of III-V nitrures. As with other epitaxial growth techniques, one of the difficulties faced for the cultivation of quality gaN by IPCH is to obtain a formation of quality germs on the substrate. A large number of substrates were used, including Al2O3 (Saphir), MgAlO4 (Spinel), SiC, Si, Si, YAG, GGG, GaAs, and ZnO (sputter-deposited). Sapphire was by far the most popular choice because of its relatively low cost, high quality, large diameter and chemical compatibility. The c-level (0001) and r-level (1 1 x 02) substrates were extensively studied. It has been found that the r level offers a higher rate of growth. However, the film GaN, with its plan A (11 2 x 0), settles parallel to the r-plane surface of the sapphire, which leads to rough and mounted surfaces, bounded by levels (1 1 x 00). GaN leaves grown on substrate levels c (0001) grow (000l) as growth is grown. However, the low surface energy of this plane results in poor heteruclation, which leads to a coarse cinematic morphology, usually dominated by the superficial/impurities characteristics of the sapphire. This effect can be well suppressed with improved wafer pole and improved heteronucleation patterns.