Study of GaN-based step-doping superjunction CAVET for further improvement of breakdown voltage and specific on-resistance

Abstract

A novel GaN-based step-doping superjunction current-aperture vertical electron transistor (SD-SJ CAVET) with SD n-and p-pillars is proposed and demonstrated by two-dimensional numerical simulations. Compared with the conventional GaN-based SJ CAVET, the greater doping concentration and more uniform electric field distributions can be realized in SD-SJ CAVET based on the special structure features, leading to the further improvement in both breakdown voltage (BV ) and specific on-resistance (R on A). Optimized results for SD-SJ CAVET with three doping parts in n-and p-pillars show that the increase in BV is ∼30% and the reduction of the corresponding R on A can be improved from 10.6% to 31.1%, with N N,1 (the doping concentration of the part N 1 in n-pillar) decreasing from 1.5×10 16 to 0.5×10 16 cm −3 , compared with SJ CAVET under the same aspect ratio. And further reduction in R on A can be achieved by adding differently doped layers in n-and p-pillars without obvious deterioration in BV. This SD-SJ CAVET can be fabricated by selective area growth technology.

Study of AlGaN/GaN Vertical Superjunction HEMT for Improvement of Breakdown Voltage and Specific On-Resistance

“…The structure could be considered as SP-SJ HEMT when N step =0. As shown in the figure, both BV and R onA will decrease with the increasing N 1 , consistent with the reported results [29], [30]. When the N step is low enough, the BV of the structure remains unchanged.…”

“…According to Ref. [29] and previous experimental results, the average concentration of the n-pillar will directly affect BV and R onA , so it is important to keep the thickness of the gradient concentration on the upper and lower sides symmetrically the same (T 1 =T 2 =T 3 =T 4 ). As shown, BV is improved if T 3 is greater than 2 µm and less than 8 µm, and there is a peak BV with T 3 =3 µm.…”

“…The current cannot flow into the p-pillar because the PN junctions formed by p-pillar/n-pillar and p-pillar/N-GaN substrate are both under reverse bias conditions. The current along the top of the n-pillar is cut down from left to right by the depletion effect [29], [30]. The special P-gate can shrink the depletion region on the right significantly, so the current density can be increased using this method.…”

Design of the GaN based CAVET with SiO2–InGaN hybrid current blocking layer

“…(CAVETs) [13,14], metal-oxide-semiconductor field-effect transistors (MOSFETs) [15,16] and FinFETs [17,18], among which CAVET is a widely studied structure. In the study of CAVET, P-GaN current-blocking layer (CBL) will have avalanche breakdown prematurely, while SiO 2 CBL has been proposed and studied because of its large band gap [19][20][21].…”

Expression set for epitaxial layer design in power MOSFET

“…This dissipated power limits the current-handling capability of the device as well as the efficiency of the whole system. So the relation between the specific on-resistance and the breakdown voltage is a great concern in device design and parameter selection for the epitaxial layer [9][10][11][12][13][14][15][16][17][18]. Thanks to the Fulop model [1], i.e.…”