Simulation Study on Electrical Characteristics of a Trench Terminated Ga2O3/Diamond Heterojunction Diode

doi:10.16553/j.cnki.issn1000-985x.2026.0065

Abstract

Abstract: Gallium oxide （Ga₂O₃） has attracted widespread attention due to its excellent properties such as wide bandgap and high breakdown field strength. However， the application of Ga₂O₃ in power devices is limited by its low intrinsic thermal conductivity and the lack of effective p-type doping. It is heterogeneously integrated with p-type semiconductor materials with high thermal conductivity， which is considered to be one of the effective solutions to solve the problem of Ga₂O₃. Diamond materials have extremely high thermal conductivity and can achieve controlled p-type doping， and it can be used to construct heterojunction devices with n-type Ga₂O₃， by which the shortcomings of Ga₂O₃ are compensated. In order to improve the breakdown characteristics of Ga₂O₃/diamond heterojunction diodes， a groove terminal structure is proposed to introduce a trench terminal structure into Ga₂O₃/diamond heterojunction， in order to increase the breakdown voltage of the device by improving the electric field. Systematic simulations were conducted using Sentaurus TCAD to evaluate the effects of trench width， depth， and filling dielectric on breakdown voltage. The results show that increasing the trench width significantly raises the breakdown voltage from 347.8 V to 1 197.85 V， an increase of 244.4%. A further increase in trench depth enhances the voltage to 1 334.51 V. In terms of filling media， compared with air， silica （SiO₂）， alumina （Al₂O₃） and hafnium dioxide （HfO₂）， SiO₂ has become the optimal medium choice due to its stable electrical characteristics and significant improvement effect on breakdown voltage. This study offers theoretical guidance for the design and optimization of Ga₂O₃/diamond devices.

Key words: Ga₂O₃; diamond; heterojunction diode; breakdown voltage; trench termination; electric field crowding

CLC Number:

SUN Congshan, HU Jichao, DONG Linpeng, PENG Bo, SU Han. Simulation Study on Electrical Characteristics of a Trench Terminated Ga₂O₃/Diamond Heterojunction Diode[J]. Journal of Synthetic Crystals, 2026, 55(8): 1266-1273.

Figures/Tables 8

Fig.1 Ga2O3/diamond heterojunction PiN diodes. （a） Without termination structures；（b） trenched termination structures

Table1 Related parameters of Ga2O3 and diamond materials

Parameter	Ga₂O₃	Diamond
Band gap， E_g/eV	4.85	5.44
Electron mobility， μ/（ cm²·V^-1·s^-1 ）	300	2 000
Dielectric constant， κ_s	10.0	5.7
Electron affinity， χ/eV	3.7	1.3
Valence band state density， N_C/cm^-3	3.72×10¹⁸	1.0×10²⁵
Conduction band state density， N_V/cm^-3	1.16×10¹⁹	1.0×10²⁶
Electronic effective quality， m_e/m₀	0.28	0.28
Breakdown field strength， E_c/（MV·cm^-1）	8	10
Thermal conductivity， λ/（W·cm^-1·K^-1）	0.27	20

Table 2 Parameter of vanOverstraeten of Ga2O3 and diamond materials

Parameter	Value
Parameter	Electrons（Ga₂O₃）	Holes（Diamond）
a/cm^-1	7.06×10⁵	1.94×10⁸
b/（V·cm^-1）	2.10×10⁷	7.75×10⁶
E₀/（V·cm^-1）	4.00×10⁵	4.00×10⁵
$ℏ ω o p$ /eV	0.063	0.165

Table 2 Parameter of vanOverstraeten of Ga2O3 and diamond materials

Parameter	Value
Parameter	Electrons（Ga₂O₃）	Holes（Diamond）
a/cm^-1	7.06×10⁵	1.94×10⁸
b/（V·cm^-1）	2.10×10⁷	7.75×10⁶
E₀/（V·cm^-1）	4.00×10⁵	4.00×10⁵
$ℏ ω o p$ /eV	0.063	0.165

Fig.2 Diagram of the device's breakdown voltage and peak electric field strength during breakdown with trench width

Fig.3 Breakdown electric field distribution diagram of devices with different trench widths

Fig.4 Diagram of the device's breakdown voltage and peak electric field strength during breakdown with trench depth

Fig.5 Breakdown electric field distribution diagram of devices with different trench depths

Fig.6 Variation of device breakdown voltage with trench depth of different trench filling materials

References 28

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Simulation Study on Electrical Characteristics of a Trench Terminated Ga₂O₃/Diamond Heterojunction Diode

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