Abstract
Device characteristics of GaN merged P-i-N Schottky (MPS) diodes were evaluated and studied via two-dimensional technology computer-aided design (TCAD) after calibrating model parameters and critical electrical fields with experimental proven results. The device’s physical dimensions and drift layer concentration were varied to study their influence on the device’s performance. Extending the inter-p-GaN region distance or the Schottky contact portion could enhance the forward conduction capability; however, this leads to compromised electrical field screening effects from neighboring PN junctions, as well as reduced breakdown voltage. By reducing the drift layer background concentration, a higher breakdown voltage was expected for MPSs, as a larger portion of the drift layer itself could be depleted for sustaining vertical reverse voltage. However, lowering the drift layer concentration would also result in a reduction in forward conduction capability. The method and results of this study provide a guideline for designing MPS diodes with target blocking voltage and forward conduction at a low bias.
Highlights
In recent decades, extensive research efforts have been put into developing III-N-based optoelectronic and electronic devices for future lighting and high-power systems because of the III-N semiconductor’s wide energy bandgap, large critical electrical field, and good thermal dissipation capability [1,2,3,4]
The GaN SBD demonstrated so far exhibited a relatively inferior breakdown voltage when compared with GaN P-i-N diodes, partly due to the relatively high leakage current and the occurrence of peak electrical fields at the device’s surface [5,6,7,8,9]
2 kV [41], there are still a few related issues to be addressed: (1) the influence of Schottky contact/ohmic contact dimensions on the device’s characteristics is unknown, for GaN merged P-i-N Schottky (MPS) with a smooth surface configuration; and (2) the impact of drift layer background concentration on the device’s characteristics, such as blocking voltage scaling with drift layer thickness, forward current level, and so on, is still unclear
Summary
Extensive research efforts have been put into developing III-N-based optoelectronic and electronic devices for future lighting and high-power systems because of the III-N semiconductor’s wide energy bandgap, large critical electrical field, and good thermal dissipation capability [1,2,3,4]. When compared with pure SBD, the GaN MPS would withstand much higher reverse voltage and demonstrate a much lower leakage current, which is directly related to off-state power loss. The GaN MPS diodes with bumpy surfaces were reported with p-type regions formed by Mg implantation or dry etching, showing forward conduction characteristics, and good blocking performance [41]. 2 kV [41], there are still a few related issues to be addressed: (1) the influence of Schottky contact/ohmic contact dimensions on the device’s characteristics (including E-field screening capability and forward conduction) is unknown, for GaN MPSs with a smooth surface configuration; and (2) the impact of drift layer background concentration on the device’s characteristics, such as blocking voltage scaling with drift layer thickness, forward current level, and so on, is still unclear. The results provided in this study could serve as an example guideline to design MPSs with target blocking voltage and forward current at a low forward voltage
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