Results of Electrical Activation

One probiem, when evaiuating dopant activation, is that we can oniy measure secondary effects of the eiectricaiiy active dopants. The chemicai concentration of 

Making comparisons between literature data using different measurement techniques is therefore many times not possible. In addition, there is the problem with surface decomposition at higher annealing temperatures, discussed in Section 4.3.1, that may strongly affect the formation and reproducibility of electrical contacts produced on implanted and annealed material. In this section we will nevertheless try to evaluate and compare recent achievements in this important field and describe a selected number of recent results on activation studies on both donors and acceptors. 

Donor ions have been somewhat neglected and one reason may be that the considerably smaller ionization energies reduce the importance of having full activation of implanted donor atoms research has therefore been concentrated on the acceptors. Another reason may also be that many of the expected SiC bipolar power-device applications require a thick low-doped n-type drift region grown by CVD in combination with a p-type emitter preferably manufactured by implantation. However, many transistor applications and also contacts to n-type material benefit from 

For implanted acceptor activation there have been several reviews during the last few years since Troffer et al. s often-cited paper on boron and aluminum from 1997 [88]. Aluminum is now the most-favored choice of acceptor ion despite the larger mass, which results in substantially more damage compared with implanted boron. Mainly it is the high ionization energy for boron that results in this choice, as well as its low solubility. In addition, boron has other drawbacks, such as an ability to form deep centers like the D-center [117] rather than shallow acceptor states and, as shown in Section 4.3.2, boron ions also diffuse easily at the annealing temperatures needed for activation. The diffusion properties may be used in a beneficial way, although it is normally more convenient if the implanted ion distribution is determined by the implant conditions alone. 

That the effective hole masses, or the density of states, is a complicated matter in SiC is well described in a review by Gardner et al. [118]. This article treats in some detail the valence band and estimates the contribution from the three top-most bands to the density of states, including the temperature dependence. Using the estimated effective mass the authors attempt to calculate the activation (i.e., the ratio of implanted and electrically active Al ions), and they achieve an activation of 37% of the implanted Al concentration of 10 cm after an anneal at 1,670°C for about 10 minutes. 

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EMG is a method to record the action potential along the muscle fiber s surface as a result of electrical activities of many motor units [4, 5], Application of EMG involved in medical research, sport training, rehabilitation, and ergonomics. Maximal Voluntary Contraction (MVC) is defined as a method to normalize the recorded data in percentage in order to standardize them. It solves the problem of how effective is a muscle in achieving a required task and what capacity level of muscle did the task [6]. 

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