Oxidized metal Schottky contact with high-κ dielectric field plate for low-loss high-power vertical β-Ga2O3 Schottky diodes

Abstract

We report on vertical β-Ga2O3 power diodes with oxidized-metal Schottky contact (PtOx) and high permittivity (high-κ) dielectric (ZrO2) field plate to improve reverse blocking at both Schottky contact surfaces and edges. The PtOx diodes showed excellent forward transport with near unity ideality factor and similar minimum specific on-resistance as Pt. Moreover, the PtOx contacts facilitated higher breakdown voltage and lower leakage current due to their higher Schottky barrier height (SBH) by more than 0.5 eV compared to that of Pt. Most importantly, the reduced off-state leakage of PtOx diodes enabled orders of magnitude less power dissipation than Pt ones for all duty cycles ≤0.5, indicating their great potential to realize low-loss and efficient, high-power β-Ga2O3 switches. The ZrO2 field-oxide further reduced edge leakage with a consistent increase in breakdown voltage. Device simulation demonstrated that the high permittivity of ZrO2 also led to the peak electric field occurring in β-Ga2O3 instead of the dielectric. These results indicate that the combined integration of oxidized-metal contacts to increase SBH and high-κ dielectric field plate to assist edge termination can be promising to enhance the performance of vertical β-Ga2O3 Schottky diodes.

Photosensitive and Rectifying Properties of Ga2O3 Described by Polaronic Screened Electrons and Internal Potentials

“…They are independent of the geometry and the device layout of the electrodes, but they can be optimized by the metal-specific electron densities and preparation-induced surface quality of the metal electrode, in agreement with experimental findings. [1][2][3][4][5][6][7][8][9][10][11][12][48][49][50][51][52][53]59,60,64,65 The value of η pair considers the large (>100) variations of the Richardson constant for different electrode metals. 62 In addition, V Xdipole monitors the electrode quality with values between 0.1 eV up to 1.5 eV 59,60 and can be minimized by in situ prepared electrodes.…”

“…In Figure a, we demonstrate the increase of the [B 4π ] by the dipole V pair = 2.5 eV (δΓ = 0.3); it reduces the range of [P 1π ] = [P 3π ] to N π (0.2) [1.6 × 10 11 cm –3 ]. This situation defines the blocking density N blocking , a key feature for Ga 2 O 3 devices such as UV absorbers and rectifiers. − ,− The regimes of the dominant B 2π and B 6π BiPs appear on top of the [P 1π ] = [P 3π ] range (the lower limit of the B 4π level). They exist only when [P 1π ] ≠ [P 3π ] and one of the LaPs dominate, while the concentration of its counterpart is diminished accordingly.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][48][49][50][51][52][53]59,60,64,65 The value of η pair considers the large (>100) variations of the Richardson constant for different electrode metals. 62 In addition, V Xdipole monitors the electrode quality with values between 0.1 eV up to 1.5 eV 59,60 and can be minimized by in situ prepared electrodes. These two parameters may also be used to modify the size and position of the red (Richardson) box in Figures 4b and 6b for novel carrier characteristics.…”

2.1 kV (001)-β-Ga2O3 Vertical Schottky Barrier Diode with High-k Oxide Field Plate

“…The lack of p-type doping in β -Ga 2 O 3 prevents using such approaches and poses fundamental challenges in device design. Alternative approaches have been explored over the years to address the issue of edge terminations in β -Ga 2 O 3 based devices 5,20,21 . Field plating is one such edge termination technique which is used in β -Ga 2 O 3 based devices to reduce electric field crowding near device edges and corners.…”

“…A peak electric field of 8-9 MV/cm was estimated at anode edges suggesting the lo- We have also analyzed the power losses in these field-plated and non-field-plated SBDs. The power loss in a diode is a combination of static and switching power losses and can be estimated using (1) 21 ,…”