AlGaN/GaN Heterojunction Bipolar Transistors With High Current Gain and Low Specific on-Resistance

N-p-n AlGaN/GaN heterojunction bipolar transistors (HBTs) on sapphire substrates with high current gain
$\beta $
of 129, low specific ON-resistance (
${R}_{ \mathrm{\scriptscriptstyle ON},\text {sp}}{)}$
of 0.28
$\text{m}\sf \Omega \cdot $
cm2 and high current density
${J}_{C}$
of ~15 kA/cm2 (if normalized to emitter area,
${R}_{ \mathrm{\scriptscriptstyle ON},\text {sp}} \sim 0.15 \text{m}\sf \Omega \cdot \text{m}^{{2}}$
and
${J}_{C} \sim 28.4$
kA/cm2) have been demonstrated. The analysis of component of
${R}_{ \mathrm{\scriptscriptstyle ON},\text {sp}}$
yields the collector resistance is ~5.2% of the total
${R}_{ \mathrm{\scriptscriptstyle ON},\text {sp}}$
, showing the low ON-resistance advantage of GaN HBTs. The open-base avalanche breakdown voltage (BVCEO) is ~160 V. High-temperature performance of GaN HBT is also evaluated. The
${R}_{ \mathrm{\scriptscriptstyle ON},\text {sp}}$
is reduced as temperature increasing in the range of 25 °C–100 °C due to enhanced hole concentration in the base layer. The cutoff frequency (
${f}_{T}{)}$
of greater than 4 GHz is determined at
${V}_{\text {CE}} =$
9 V. These results dominate that GaN HBTs have been anticipated to become a new technology for next-generation power switches and RF power amplifier circuit.