KV-Class and Low RON Vertical β-Ga2O3 HEMT-CAVET Power Switch

Background

Beta-gallium oxide (β-Ga2O3) has become a promising candidate for high-power, high-voltage, and high-frequency applications due to its ultrawide bandgap (-4.8 eV), high critical electric field (-8 MV/cm), and large Baliga’s figure of merit. Compared with lateral devices such as high electron mobility transistors (HEMTs), vertical devices have tremendous advantages in high power applications, including higher voltage and current handling capability, immunity to surface-related issues, simpler cooling requirements, smaller chip area, and easy scalability.

Recently, β-Ga2O3-based vertical transistors such as current aperture vertical electron transistors (CAVETs) and vertical fin-MOSFETs have been demonstrated. However, their device performance is still far from the β-Ga2O3 material limit. Deep etching is required in β-Ga2O3 fin-MOSFETs to overcome drain-induced barrier lowering (DIBL), and the resulting low breakdown voltage (BV), which is challenging in fabrication.

There are many issues to be solved for β-Ga2O3 CAVETs, including low BV, small gate voltage swing, high reverse leakage, high ON-state resistance (RON), and difficulty in realizing enhancement-mode (E-mode) due to the lack of suitable p-type doping. For power electronics, E-mode or normally-off devices are highly desired for fail-safe operation and simpler driver circuits.

Invention Description

Researchers at Arizona State University have developed a novel power switch in a β-Ga2O3 CAVET configuration by introducing delta-doped β-(AlxGa1-x)2O3/Ga2O3 heterostructure. This design reduces the ON-state resistance (RON) and improves electron modulation due to a confined two-dimensional electron gas (2DEG) channel. In initial tests, the BV of the current blocking layer (CBL) region increased linearly with the acceptor doping concentration. This design can be developed into kV-class low RON β-Ga2O3 3 HEMT-CAVETs for high power, high voltage, and high frequency applications.

Potential Applications

• Power conversion switch for power circuits
• Efficient voltage switch for high voltage applications

Benefits and Advantages

• Low reverse leakage & high breakdown voltage
• Incorporates vertical current handling structure instead of lateral current handling structure (lower network losses)
• Enhances power conversion efficiency (low ON resistance and high off-state breakdown voltage

Related Publication: Design of kV-Class and Low RON E-Mode β-Ga2O3 Current Aperture Vertical Transistors with Delta-Doped β-(AlxGa1-x)2O3/Ga2O3 Heterostructure