An AlGaN/GaN HEMT with a reduced surface electric field and an improved breakdown voltage

Abstract

A reduced surface electric field in an AlGaN/GaN high electron mobility transistor (HEMT) is investigated by employing a localized Mg-doped layer under the two-dimensional electron gas (2-DEG) channel as an electric field shaping layer. The electric field strength around the gate edge is effectively relieved and the surface electric field is distributed evenly as compared with those of HEMTs with conventional source-connected field plate and double field plate structures with the same device physical dimensions. Compared with the HEMTs with conventional sourceconnected field plates and double field plates, the HEMT with a Mg-doped layer also shows that the breakdown location shifts from the surface of the gate edge to the bulk Mg-doped layer edge. By optimizing both the length of Mg-doped layer, Lm, and the doping concentration, a 5.5 times and 3 times the reduction in the peak electric field near the drain side gate edge is observed as compared with those of the HEMTs with source-connected field plate structure and double field plate structure, respectively. In a device with V GS = −5 V, Lm = 1.5 µm, a peak Mg doping concentration of 8×10 17 cm −3 and a drift region length of 10 µm, the breakdown voltage is observed to increase from 560 V in a conventional device without field plate structure to over 900 V without any area overhead penalty.

A hybrid simulation technique for electrothermal studies of two-dimensional GaN-on-SiC high electron mobility transistors

“…35 For 2DEG, it is possible to compute the exact scattering rates as a function of wave vectors by Fermi's golden rule. 33,39,40 However, this may largely increase the computational load and is not suitable for the hybrid simulation technique. In the simplified treatment, the 3D electronphonon scattering formulation has been generally adopted in the literature 14,19,24,34,35 and is justified by good fittings with experiments.…”

Improvement of drain breakdown voltage with a back-side gate on AlGaN/GaN high electron mobility transistors

“…Thus, drain breakdown voltage is enhanced and drain current collapse is lessened. [11][12][13][14][15][16][17][18] Gate field plates have also been implemented to demonstrate a drain breakdown voltage of 570 V by extending the gate on top of silicon nitride (SiN x ) toward the drain contact. 19 Hikita et al opened a via through the epitaxial layer to the front side of the device to connect the frontside source to a backside grounding electrode and achieved both low on-state resistance (1.9 mX cm 2 ) and high breakdown voltage of 350 V. 20 Lu et al 18 also demonstrated the effect of source field plate, which improved the breakdown voltage from 55 to 155 V.…”

Quantum Mechanical Analysis of GaN Nanowire Transistor for High Voltage Applications

“…Gallium Nitride (GaN) has now been widely used for high electron mobility transistors (HEMT) due to its high mobility and also because of its wide bandgap which endows it the property of high breakdown voltage and allows it to be used for high voltage applications [8][9]. GaN nanowires have been in fabrication processes for a long time [10][11] and been used for photo-detection and photoluminescence applications [12][13].…”