Abstract
P-grid is a typical feature in power devices to block high off-state voltage. In power devices, the p-grid is routinely coupled to an external electrode with an Ohmic contact, but Schottky contact to the p-grid is also proposed/adopted for certain purposes. This work investigates the role of contact to p-grid in power devices based on the commonly adopted technology computer-aided design (TCAD) device simulations, with the silicon carbide (SiC) junction barrier Schottky (JBS) diode as a case study. The static characteristics of the JBS diode is independent of the nature of the contact to p-grid, including the forward voltage drop (VF) and the breakdown voltage (BV). However, during the switching process, a Schottky contact would cause storage of negative charges in the p-grid, which leads to an increased VF during switching operation. On the contrary, an Ohmic contact provides an effective discharging path for the stored negative charges in the p-grid, which eliminates the dynamic degradation issues. Therefore, the necessity of an Ohmic contact to p-grid in power devices is clarified.
Highlights
Power devices typically feature p-grids inside the device active regions to block the high off-state voltage or to protect certain vulnerable structures [1]
junction barrier Schottky (JBS) diode is the device under test (DUT)
silicon carbide (SiC) JBS diode is the device under test (DUT)
Summary
Power devices typically feature p-grids inside the device active regions to block the high off-state voltage or to protect certain vulnerable structures [1]. For an insulated gate bipolar transistor (IGBT), a Schottky contact to the p-body has been proposed to enhance the minority carrier concentration near the emitter side without any sacrifice in the off-state breakdown voltage (BV) [8]. In the emerging gallium nitride (GaN) power transistors, a Schottky contact to the p-region is wide used to enlarge the gate voltagecontact swing to [9,10], or explored as a method adjustthe the threshold voltag gallium nitride (GaN). This work aims to discuss the role of the contact to p-grid in certain power devices, whos poor reverse recovery can be avoided [16,17]. This work aims to discuss contacts the roleare of under the contact to p-grid in certain power devices, study. SiC power devices have attracted worldwide attention because thework high critical breakdow whose metal/p-region contacts are under investigation. Simulations aredesign deployed to reveal the internal dynamics of the devices
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