Novel Enhance-Mode AlGaN/GaN JFET With BV of Over 1.2 kV Maintaining Low RON,sp

The traditional GaN high electron mobility transistor (GaN HEMT) is in the ON-state under zero gate bias, which does not meet the requirements of practical application. Therefore, in the application, it is necessary to continuously increase the negative voltage to the power grid to stop the equipment, which will increase the system cost and limit the improvement of system reliability. Therefore, the realization of enhanced AlGaN/GaN HEMT is of great significance. In order to further improve the breakdown characteristics and get a positive threshold voltage for GaN HEMT, a new enhance-mode junction AlGaN/GaN HEMT (EM-AlGaN/GaN JFET) structure is proposed in this article for the first time with the high breakdown voltage (BV) by introducing p-GaN buried layer into GaN epitaxial buffer layer to form p-n junction. The Sentaurus TCAD software is used to simulate the EM-AlGaN/GaN JFET. The simulation results show that the positive threshold voltage (
${V}_{\text{th}}$
) of 1.21 V is obtained, while the BV of the novel EM-AlGaN/GaN JFET is about 1283 V. The corresponding low-specific ON-resistance
${R}_{ \mathrm{\scriptscriptstyle ON},\text{sp}}$
is 2.44 m
$\boldsymbol {\Omega } \cdot $
cm
²
. The switching device figure of merit (FOM) is further improved. The FOM of 679 MW
$\cdot $
cm
⁻²
(FOM = BV
²
/
${R}_{ \mathrm{\scriptscriptstyle ON},\text{sp}}$
) is 1.52 times of the FOM (447 MW
$\cdot $
cm
⁻²
) of conventional AlGaN/GaN HEMT. We can see that the introduction of p-GaN reduces the concentration of two-dimensional electron gas (2DEG) in the ON-state. In the OFF-state, the gate of the p-n junction forms a higher built-in potential and modulates the electric field distribution to get high BV. Due to the heterojunction polarized 2DEG, it has a lower
${R}_{ \mathrm{\scriptscriptstyle ON},\text{sp}}$
than the conventional GaN JFET. It has a good application prospect in the field of power electronic devices.