Polarization-induced (Pi) distributed or bulk doping in GaN, with a zero dopant ionization energy, can reduce temperature or frequency dispersions in impurity-doped p–n junctions caused by the deep-acceptor-nature of Mg, thus offering GaN power devices promising prospects. Before comprehensively assessing the benefits of Pi-doping, ideal junction behaviors and high-voltage capabilities should be confirmed. In this work, we demonstrate near-ideal forward and reverse I–V characteristics in Pi-doped GaN power p–n diodes, which incorporates linearly graded, coherently strained AlGaN layers. Hall measurements show a net increase in the hole concentration of 8.9 × 1016 cm−3in the p-layer as a result of the polarization charge. In the Pi-doped n-layer, a record-low electron concentration of 2.5 × 1016 cm−3is realized due to the gradual grading of Al0-0.72GaN over 1 μm. The Pi-doped p–n diodes have an ideality factor as low as 1.1 and a 0.10 V higher turn-on voltage than the impurity-doped p–n diodes due to the increase in the bandgap at the junction edge. A differential specific on-resistance of 0.1 mΩ cm2is extracted from the Pi-doped p–n diodes, similar with the impurity-doped counterpart. The Pi-doped diodes show an avalanche breakdown voltage of ∼1.25 kV, indicating a high reverse blocking capability even without an ideal edge-termination. This work confirms that distributed Pi-doping can be incorporated in high-voltage GaN power devices to increase hole concentrations while maintaining excellent junction properties.
- Award ID(s):
- 1719875
- NSF-PAR ID:
- 10227972
- Date Published:
- Journal Name:
- IEEE transactions on electron devices
- ISSN:
- 1557-9646
- Page Range / eLocation ID:
- 1-5
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
-
more » « less
Traditional mesa terminations require precise angle design to reduce the electric field at the edge and surface treatment to reduce etch damage. Otherwise, the device usually suffers a premature breakdown. This work proposes the use of easy-to-implement hydrogen plasma treatment to solve the premature breakdown caused by mesa and demonstrates the avalanche capability in GaN-on-GaN p-i-n diodes. The breakdown electric field when the avalanche occurred was ∼2.3 MV/cm at room temperature for a GaN drift layer with a doping concentration of ∼7 × 1015 cm−3, which is consistent with the theoretical value. The temperature coefficient of the avalanche breakdown voltage of the devices was 4.64–4.85 × 10−4 K−1. This work shows a simple and effective approach to achieve avalanche capability in vertical GaN power devices, which can serve as an important reference for the future development of efficient and robust GaN power electronics.
-
This work demonstrates a novel junction termination extension (JTE) with a graded charge profile for vertical GaN p-n diodes. The fabrication of this JTE obviates GaN etch and requires only a single-step implantation. A bi-layer photoresist is used to produce an ultra-small bevel angle (~0.1°) at the sidewall of a dielectric layer. This tapered dielectric layer is then used as the implantation mask to produce a graded charge profile in p-GaN. The fabricated GaN p-n diodes show a breakdown voltage ( BV ) of 1.7 kV (83% of the parallel-plane limit) with positive temperature coefficient, as well as a high avalanche current density over 1100 A/cm 2 at BV in the unclamped inductive switching test. This robust avalanche is ascribed to the migration of the major impact ionization location from the JTE edge to the main junction. This single-implant, efficient, avalanche-capable JTE can potentially become a building block of many vertical GaN devices, and its fabrication technique has wide device and material applicability.more » « less
-
more » « less
Large area (1 mm2) vertical NiO/
β n-Ga2O/n+Ga2O3heterojunction rectifiers are demonstrated with simultaneous high breakdown voltage and large conducting currents. The devices showed breakdown voltages (VB) of 3.6 kV for a drift layer doping of 8 × 1015cm−3, with 4.8 A forward current. This performance is higher than the unipolar 1D limit for GaN, showing the promise ofβ -Ga2O3for future generations of high-power rectification devices. The breakdown voltage was a strong function of drift region carrier concentration, with VBdropping to 1.76 kV for epi layer doping of 2 × 1016cm−3. The power figure-of-merit, VB2/RON, was 8.64 GW·cm−2, where RONis the on-state resistance (1.5 mΩ cm2). The on-off ratio switching from 12 to 0 V was 2.8 × 1013, while it was 2 × 1012switching from 100 V. The turn-on voltage was 1.8 V. The reverse recovery time was 42 ns, with a reverse recovery current of 34 mA. -
more » « less
A top-illuminated deep-ultraviolet Al0.6Ga0.4N p-i-n avalanche photodiode (APD) structure was designed and grown by metalorganic chemical vapor deposition on an AlN bulk substrate and on two different quality AlN/sapphire templates, and APDs were fabricated and tested. The APD devices with a circular diameter of 20 μm have demonstrated a distinctive reverse-bias breakdown behavior. The reverse breakdown voltage of the APDs is approximately −140 V, which corresponds to a breakdown electric field of 6–6.2 MV/cm for the Al0.6Ga0.4N material as estimated by Silvaco TCAD simulation. The APDs grown on the AlN bulk substrate show the lowest leakage current density of <1 × 10−8 A/cm2(at low reverse bias) compared to that of the devices grown on the AlN templates. From the photocurrent measurement, a maximum gain (current limited) of 1.2 × 104is calculated. The average temperature coefficients of the breakdown voltage are negative for APD devices fabricated from both the AlN bulk substrate and the AlN templates, but these data show that the coefficient is the least negative for the APD devices grown on the low-dislocation-density AlN bulk substrate.
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- The DOI is not currently available.
