1950°C Post Implantation Annealing of Al+ Implanted 4H-SiC: Relevance of the Annealing Time
About: This article is published in ECS Journal of Solid State Science and Technology.The article was published on 2016-01-01 and is currently open access. It has received 10 citation(s) till now.
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SiC: Relevance of the annealing
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- Anyway, the cost of this technology and the difficulty of its control are so high that embedded epitaxial growth is limited to the fabrication of device channel regions while for the device termination regions or for the test of new doping profiles, ion implantation remains the preferred technology.
- 10–13 Therefore, further investigations appear as necessary for understanding the effect of the duration of the post implantation annealing on SiC. zE-mail: firstname.lastname@example.org material cannot exceed the value corresponding to the solid solubility of the implanted species in the semiconductor lattice at the temperature of post implantation annealing.
- At the same time, for quenching the annealing process at the end of the time spent at 1950◦C, a fast cooling rate has been used too.
- Post implantation annealing processes were performed in high purity Ar ambient.
- Four samples with different annealing times of 5–10–25–40 min were processed.
- Four point sheet resistance and Hall effect measurements on the van der Pauw devices were performed in vacuum at different temperatures in the range 30–680 K.
- Measurements of the same sample were taken during heating and during cooling, moreover they were repeated at distance of time.
- Fig. 1a shows the SIMS Al depth profiles of the 5 min and 40 min annealed specimens.
- Every other sample of this study had an Al depth profile overlapping with those of Fig. 1a.
- Moreover, at high T, these values decrease with the increasing of the annealing time, varying from 116 meV for 5 min annealing to 107 meV for 25–40 min annealing.
- The cross-point between the two straight lines that interpolate the 5–10 min data and the 25–40 min ones falls at ≈22 min.
- Moreover, till present the authors have measured neither a profile shift nor a dopant in/out diffusion for implanted Al in 4H-SiC.
- Based on all that, the authors say that the SIMS measurements of the Al implanted 4H-SiC samples of this study (see Fig. 1a) point out that the Al depth distribution is not significantly affected by the duration of the annealing time.
- The exponential trends of the high T region of the sheet resistance (Fig. 2a) and of the drift hole area density (Fig. 4a) curves, together with their thermal activation energies, supports the statement that at high T the carrier transport takes place in the extended states of the valence band.
- This answer can be found by considering the high T region of both the sheet resistance (Fig. 2b) and the drift hole area density (Fig. 4b) curves.
- All that agrees with the hypothesis of an increasing of the Al acceptor concentration up to saturation with the increase of the annealing time.
- This study shows that the electrical activation of Al implanted in 4H-SiC with concentrations lower than its solubility values at the annealing temperature increases with the increasing of the annealing time up to saturation.
- Al implanted HPSI 4H-SiC, 400◦C implantation temperature, and 1950◦C post implantation annealing temperature, the minimum time to obtain the maximum Al electrical activation is about 22 min.
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...boron (B) are most common, for which the effects of the postimplantation annealing are yet not fully understood ....
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Q1. What are the contributions in "1950°c post implantation annealing of al+ implanted 4h-sic: relevance of the annealing time" ?
In this paper, the authors showed that the electrical activation of Al implanted in 4H-SiC with concentrations lower than its solubility values at the annealing temperature increases with the increasing of the annesaling time up to saturation.