In this study, important results have been summarized in previous section.
However, many works are worthy for further investigation. They are listed here.
4. The smoother and stronger DLTS signal can be obtained by shortening the sampling delay time. A much better signal can be obtained like commercial system.
However, for the DLTS signal consist of multiple traps, and the improvement in signal intensity still does not help in distinguishing them. It’s better to apply a lock-in amplifier such as SR830 or Laplace DLTS by computer computation. This helps the verification and extraction of defect energy so that more accurate result can be obtained.
5. The other works on DLTS system is to check the lowest defect density that can be measured by our DLTS system. The best choice is the 1600 oC annealing sample, which contains only one kind of defect. In addition, the defect density can be reduced by oxidation. By repeating the oxidation process, we can get the detect limitation of our DLTS system.
6. For TJBS diodes, the fabrication of device should be realized. Besides, different parameters can be involved in the reticle design to verify the results of simulation.
7. The cut-in voltage of JBS diodes is influenced by depletion region. By applying low Schottky barrier height metal, we can change the Schottky metal width to
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modulate the cut-in voltage. In addition, the cut-in voltage modulation can be achieved by nitrogen implantation to contract the depletion region.
8. The transition voltage of TJBS diode is affected by the voltage drop on the pn junction, so the doping concentration and thickness of the epi-layer have its own influence, too. These factors would affect the device deign and should be studied.
9. The breakdown of TJBS diode occurs at the trench corner. Instead of a right angle, the trench corner can be a bevel or a rounding corner in practice. Different shapes of trench may also have different influences on the forward characteristics of TJBS diodes. The profile of p+ implantation can be also studied to prevent the premature of breakdown in TJBS diode.
10. For trench with a gradual sidewall slope, the p-type ion implantation on the sidewall is relative easy to occur. With p-type doping on sidewall, a stronger JFET effect is expected, but the influence on the breakdown voltage is un-cleared.
Besides, with different p-type concentration, different phenomenon would be observed, too.
11. The trench structure has been applied in JBS diodes to become TJBS diodes.
Hence, it can be applied into the edge termination structure with above mentioned works. The effect of trench shape, implantation on sidewall or top of the un-etched epi-layer, and the trench depth can be taken into consideration to evaluate the trench termination structure.
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