A 1.86-kV double-layered NiO/ β -Ga2O3 vertical p–n heterojunction diode

Abstract

In this Letter, high-performance vertical NiO/β-Ga2O3 p–n heterojunction diodes without any electric field managements were reported. The devices show a low leakage current density and a high rectification ratio over 1010 (at ±3 V) even operated at temperature of 400 K, indicating their excellent thermal stability and operation capability at high temperature. Given a type-II band alignment of NiO/β-Ga2O3, carrier transport is dominated by the interface recombination at forward bias, while the defect-mediated variable range hopping conduction is identified upon strong reverse electric field. By using the double-layer design of NiO with a reduced hole concentration of 5.1 × 1017 cm−3, the diode demonstrates an improved breakdown voltage (Vb) of 1.86 kV and a specific on-resistance (Ron,sp) of 10.6 mΩ cm2, whose power figure of merit (Vb2/Ron,sp) has reached 0.33 GW/cm2. The high breakdown voltage and low leakage current are outperforming other reported Ga2O3 based p–n heterojunctions and Schottky barrier diodes without field plate and edge termination structures. TCAD simulation indicates that the improved Vb is mainly attributed to the suppression of electric field crowding due to the decreased hole concentration in NiO. Such bipolar heterojunction is expected to be an alternative to increase the breakdown characteristics of β-Ga2O3 power devices.

β‐Gallium Oxide Devices: Progress and Outlook

“…Using this feature, p–n heterojunction diodes between n‐ and p‐type amorphous oxides such as Cu 2 O and NiO have been developed. [ 51–53 ] Good device characteristics with < 10 mΩ cm 2 and > 1 kV were achieved for both the amorphous materials.…”

“…Benchmark – performance of the state‐of‐the‐art SBDs [ 47–50,54–56 ] and p–n heterojunction diodes [ 51–53 ] is shown in Figure . The characteristics of both types of diodes have already exceeded the Si theoretical limit but never reached those of SiC and GaN.…”

Comprehensive Study and Optimization of Implementing p-NiO in β-Ga2O3 Based Diodes via TCAD Simulation

“…A temporary solution to resolve the p-type issue is by applying other p-type semiconductors instead of p-type Ga 2 O 3 to fabricate the HJ architecture. Recently, some preliminary studies have combined p-type oxides with n-Ga 2 O 3 to construct HJPN diodes for high BV purposes [16][17][18][19]. Among those p-type semiconductors, NiO is a good alternative to p-type Ga 2 O 3 owing to its wide energy band gap.…”

“…NiO is a material with a rock salt crystal structure and its band gap value depends on the growth condition which is between 3.8 and 4.2 eV [20][21][22]. Further, values for its hole mobility between 0.12 and 0.94 cm 2 /V s have been reported [17]. Although the NiO/Ga 2 O 3 HJ diodes have been reported to improve the BV, the performance of those diodes is still far away from its ideal value and is facing significant material and device structure design challenges.…”

Field-Plated NiO/Ga2O3 p-n Heterojunction Power Diodes With High-Temperature Thermal Stability and Near Unity Ideality Factors

“…Benefiting from the superior material advantages of ultra-wide bandgap, enhanced critical electric field and the availability of large-sized substrates, high performance β-Ga 2 O 3 -based unipolar devices such as Schottky barrier diodes (SBDs) and MOSFET switches have been demonstrated [1][2][3]. To enhance the reserve blocking capability, the NiO/Ga2O3 p-n heterojunction diodes (HJDs) has been demonstrated as a very promising strategy to realize advanced bipolar rectifiers, which alternatively overcomes the technological bottleneck of p-type Ga 2 O 3 [4][5][6][7][8][9]. These developed p-n HJDs have exhibited large current outputs, low specific on-resistances (Ron,sp) and enhanced breakdown voltages (BVs), which are of particular interest and importance to high-power, high-temperature and low-losses applications [6][7][8][9].…”