High-Temperature Performance of AlGaN/GaN MOSHEMT With $\hbox{SiO}_{2}$ Gate Insulator Fabricated on Si (111) Substrate

Abstract

The dc operation of high-quality AlGaN/GaN metal–oxide–semiconductor high-electron-mobility transistors (MOSHEMTs) on Si (111) substrates, fabricated using <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{SiO}_{2}$ </tex></formula> as the gate insulator, is investigated for the first time as a function of ambient temperature <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$(T)$</tex></formula> . <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$I$</tex></formula> – <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$V$</tex></formula> and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$C$</tex> </formula> – <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$V$</tex></formula> characteristics of these depletion-mode devices are studied in the temperature range of 25–200 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ}\hbox{C}$ </tex></formula> , and the results are compared to those of reference AlGaN/GaN HEMTs processed on the same wafer and of identical geometry. For devices with an 8- <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu\hbox{m}$</tex></formula> drain-to-source separation and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{1} \times \hbox{2.5} \times \hbox{100}\ \mu \hbox{m}^{2}$</tex></formula> gate dimensions, the maximum output current density was about 730 mA/mm at <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$+$</tex></formula> 2 V gate bias for both types of transistors. The thermal behavior of the MOSHEMTs on Si was found to resemble that of devices grown on sapphire and silicon carbide with the gate leakage current exhibiting a rapid increase with <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$T$</tex></formula> but remaining below the levels seen in the reference HEMTs. The maximum drain current also showed a relatively smaller degradation at elevated temperatures as compared to previously published data.